Can't get your PC to boot? Or just sent your boss a really embarrassing e-mail? Here's how to recover from these and ten other potential catastrophes.

Christopher Null (PC World)
 
When it comes to computers, sometimes things go south...and sometimes they go to Antarctica. If your computer won't boot or your data's gone astray, panic is soon to follow, and you might find yourself making things worse in your haste to solve the problem.

Of course, this advice won't solve every tech-related problem you may come across, but it includes some neat tricks that you may not have thought of, such as freezing a bad hard drive to get it to boot one last time so you can retrieve your data, baking your wet mobile device in an oven set on low to make it functional again, and putting a delay on your outbound e-mail so you have a chance to reconsider the flame you just wrote.

Problem: Your computer won't boot.
Likely Cause: Could be anything. Determining whether the issue stems from hardware or software is part of the fix.
The Fix: You'll have to play Sherlock Holmes to figure out what's dead. Take it step-by-step.

1. First thing: Check all cables (including the plug into the electric socket) to make sure everything is hooked up nice and tight.

2. Next, see if the power supply turns on. Listen for the sound of its fan or of your hard drive spinning. If you hear nothing, your power supply probably needs to be replaced. To confirm, consider testing the voltage output with a power-supply tester such as PC Power and Cooling's $10 ATX). Of course, you should also check your home's circuit breaker before doing major PC surgery, and try powering another device from that outlet to make sure it's getting juice.

3. If your power supply is okay but nothing appears on screen, plug in a different monitor (borrow one if you must) to ensure it's not your display that's blown. If the monitor proves to be good, try replacing the video cable. Still nothing on screen? If your drive is spinning normally, your video card is probably bad. To replace it, see our video guide, "How to Replace a Graphics Board," or use the video output integrated into your PC's motherboard, if it has that feature. While your case is open, make sure all the fans inside work when you power on the PC. You could have excess-heat issues.

4. If your monitor is working but you detect no hard-drive activity and see no display (or you see a display but the PC can't get through boot-up), reset the CMOS. Shut down the PC, unplug it, ground yourself, and take out the battery on the motherboard (click on photo above). Wait 5 minutes, and consult your PC manual or go to the vendor's Web site for instructions on resetting the CMOS jumpers. Reboot and see if that fixed the problem.

5. If the PC is still not functioning, bad RAM could be the culprit. Remove one memory module at a time (or replace each module with a known good one) and reboot after each test. Alternatively, create a free MemTest86 boot disk on another PC, and try using it to test the RAM.

6. If none of this works, your motherboard or CPU is probably damaged, and will need to be replaced (cost: $80 to $300 or more). However, your data is probably still intact and can be recovered if you install your hard drive on another system. Consider going to a repair shop for an estimate on the repair; it may be more cost-effective to replace the PC. Also, a repair shop might be your best (and only) option if your PC is a laptop.

7. Finally, if the PC's BIOS routine runs but the drive won't spin, your drive may have crashed. See "Problem: Your hard drive has crashed" for help with that.

What If It's the OS?
As dire as these hardware failures seem, you're far more likely to encounter software issues, such as Windows refusing to start or freezing while it's loading. Here's how to get back up and running if your operating system is the problem.

1. Boot into Safe Mode. As Windows starts up, press the key as directed to reach the boot menu. Select Safe Mode. Often, Windows will recover if you boot into Safe Mode and then shut down and reboot normally. With Windows Vista, you can also try the 'Repair Your Computer' option by selecting it at the boot menu (if you don't have that option, check your Vista DVD for it). You'll have various choices to aid your PC: 'Startup Repair' is worth a shot.

2. No results? Try 'Last Known Good Configuration' at the boot menu, which is especially helpful if you have recently changed hardware or drivers. If this works, remove new hardware (which may be incompatible) and roll back drivers in Device Manager. Right-click My Computer (Computer in Vista), click Hardware (in XP), and choose Device Manager.

3. If you can run Safe Mode but not regular Windows, try System Restore (via Programs, Accessories, System Tools in XP; in Vista, click Start, type system, and choose System Restore from the Programs list) to roll back your PC to when it did work. The PC might have become unstable after an automatic download and installation of an update or other unattended download (you may want to change any default settings that allow such unattended installs to happen). Run antivirus and antispyware apps in Safe Mode, too.

4. If you still can't boot, you probably have heavy-duty Windows problems. Try to boot from an emergency CD like a Knoppix disc or an Active Boot Disk, which can help you to see whether your PC will boot at all and to collect any critical files from the drive.

5. If your PC is still unstable, reinstalling Windows is probably your best bet. You can do this chore while leaving data intact by using a standard Windows installation CD. In rare cases, vendor-provided recovery disks will perform non-data-destructive OS reinstalls too; check your manual to see if yours can. See our directions on reinstalling XP and on reinstalling Vista.

How to Avoid It Next Time:
PCs typically die unexpectedly, so focus on getting up and running quickly: Turn on System Restore, keep your system-recovery discs and copies of critical apps handy for reinstalls, back up often, and keep a spare hard drive and power supply. Using a drive-image program such as the $50 Acronis True Image 10 or the $70 Norton Ghost 10 can make it much easier to restore your PC and data, too. If you can, have a second PC to use in emergencies if your main system needs repair.

Problem: No PCs show on the network.
Likely Cause: Windows is probably at fault, but the source could be hardware. An easy way to check which it is: If you can access the Internet, chances are the problem is not your hardware or drivers.
The Fix: If the problem is not hardware, start by going through the various Windows settings to see which has gone bad.

1. If you've never been able to see other computers on the network, check that they're all part of the same workgroup. (Windows Vista changes the default workgroup name.) Select Start, Run, type sysdm.cpl, and press <Enter>. Click the Computer Name tab and then the Change button, and look at the Workgroup field.

2. Next, look for duplicate IP address assignments, another common problem. Windows will usually pop up a warning about one PC being assigned an IP address that's already in use on the network. A router and/or PC reboot will often solve this; but also check that manually assigned, static IP addresses haven't been set on some systems in the same area the router uses to assign automatic IP addresses (check each PC individually by clicking Start, Run, then typing cmd /k ipconfig and pressing <Enter>).

3. Running Windows Update on all systems could solve this problem, too, particularly on XP machines. As always, check cabling and Wi-Fi settings. (Also, is the PC you want to reach actually on?)

4. Finally, make sure the printers or folders you are trying to access are shared and have the appropriate permissions for clients to read; you'll need to log in as an administrator to do this. For folders, go to Windows Explorer, right-click the folder you want to share, and select Share. For printers, go to Start, Printers and Faxes (Printers In Vista), right-click the printer you want, and choose Sharing. Remember, sharing in Vista is quite different than in XP: Make sure network discovery and file and/or printer sharing are turned on in the Network and Sharing Center.

How to Avoid It Next Time:
Once these issues are remedied, the problem should not crop up again. If it does resurface, a few reboots ought to take care of it.

Problem: Your identity has been stolen!
Likely Cause: You'll probably never know. Your credit report was illegally pulled, or your Social Security, credit card, or ATM number was scammed.
The Fix: Take these steps as soon as possible. (This section includes tips from the Federal Trade Commission.)

1. Cancel ATM/credit cards and report the issue to your credit card companies; request new account numbers if necessary. Change all PINs (even on new cards). Banks and credit card companies require notice in writing of any compromised accounts; you can use the FTC's fraud affidavit to provide that notice.

2. Change the passwords to all your financial-institution Web sites.

3. Explain the situation to the fraud department at each of the three credit reporting agencies: Equifax, 866/640-2273), Experian, 800/493-1058), and TransUnion, 800/916-8800). File forms as required.

4. Examine your credit report (each agency will provide a copy) for illegal or inaccurate listings. File forms disputing the reports as appropriate.

5. File a police report locally or where the theft took place (if you know). Ask for copies of the report; you'll need to send it to credit agencies, and you should keep one, as well.

6. File an ID theft complaint with the FTC. You can do so online via its Complaint Input Form.

How to Avoid It Next Time:
You can get one credit report free per year per credit agency; try checking one report every four months for timely monitoring. Use strong passwords and PINs (for tips on creating strong passwords, see the Privacy Watch column, "E@4#N or E@4#W? How to Remember Strong Passwords"). Don't share your Social Security number if possible. Consider limiting the business you do on the Web to sites you've vetted.

Problem: Your Net connection is dead.
Likely Cause: Your router could have seized up, sunspots might be mucking with the Web, or...
The Fix: Start with the issues you can control. Modems and routers are vulnerable to frequent crashes. A simple reboot usually corrects the problem.

1. First, try using another PC to reach the Web (you could have a faulty network card in the first machine). If you can't do that, check if your local network is working (if not, the culprit might be the router, which you may need to reboot or replace).

2. Next, see if your cable or DSL modem is displaying error lights. If it indicates trouble, unplug it. You may as well do the same for your router and shut down your PC. Wait about 30 seconds after you've unplugged your gear, and then plug everything back in and start up your PC.

3. If that doesn't work, try resetting your PC connection in Windows. The most reliable way in XP is to click Start, Run and type CMD (in Vista, type CMD at the search prompt). Then type ipconfig /renew at the terminal prompt. You'll get a similar outcome by right-clicking the network connection icon in the system tray and selecting Repair. However, I find the terminal method more effective.

4. If you're still not online and you usually connect via a wireless adapter, try plugging in directly to the router via an ethernet cable. Still not working? Try skipping the router and connecting a PC directly to the modem to further isolate the problem. Check all cables and replace them if possible. Examine cable modems for fraying on the coaxial wiring.

5. No dice? It's time to call your broadband provider to check for known outages in your area. (Don't forget to check the obvious: If you use a cable modem, is the cable TV working? Did you pay the bill?) Some providers can test your network gear remotely, as well; in some cases the ISP may need to send a reset signal to your modem. But at this point you're likely dealing with a network outage. Such outages are usually temporary, but reporting them and complaining--repeatedly--will likely result in a speedier resolution.

How to Avoid It Next Time:
Invest in backup connectivity gear--find a nearby friend whose Wi-Fi signal you can use, or buy a wireless data card and account for your laptop. Even having dial-up numbers for your ISP or an AOL or NetZero CD handy can get you online in a pinch.

Problem: Your camera, cell phone, laptop, or keyboard just got doused with water--or worse.
Likely Cause: This is one you can't blame on Microsoft.
The Fix: Water and electronics don't mix, but a little spill doesn't necessarily mean your gear is ruined. To be honest, the odds aren't great for your gadget's full recovery--but with care, you might be able to revive your hardware.

First, if the device is still on, turn it off immediately and remove any batteries, CDs, SIM cards, memory cards, and the like. For a notebook, remove any modular components like PC Cards and removable optical drives. Dry off any visible liquid with a towel. Depending on how comfortable you are with the process, disassemble the device as much as possible and as quickly as possible to improve your chances of recovering it. This is essential if you can actually hear trapped liquid sloshing around inside.

Your goal is to get the device completely dry, inside and out, as rapidly as you can. There are many ways of doing this, so from the following bag of tricks try whatever is convenient and appropriate for you. Remember that all of these "cures" can cause more damage than they repair. Luck is a major factor here.

1. Desiccants will absorb moisture. Put the device in a sealed bag with a few silica gel packets. Only brand-new packets will work--old ones will have long ago absorbed their limit in moisture. The same trick can work with regular uncooked white rice and even salt; just make sure not to get any grains inside the device. (Try wrapping your gadget in tissue paper.)

2. Heat can evaporate water. Put the device on the dashboard of your car for an afternoon (just make sure that it doesn't get hotter than about 150 degrees). If you're brave, you can try putting the device in a 150-degree oven for an hour. Keeping your cell phone in your front pants pocket all day also might warm it enough, as might a hair dryer (don't set it on high, though). Make sure the battery is removed if you try any of these tricks.

3. Alcohol attracts water. Again, this is not a trick for the faint of heart, but you can dunk a wet gadget completely in a container full of alcohol (use 99 percent rubbing alcohol, not the standard 70 percent), which will bind to the water and pour out or evaporate. Make sure you do this quickly, as alcohol can damage some kinds of plastics.

4. If the device has (or is) a keyboard, put it upside down for a spell to give the liquid a chance to drain out.

5. If you managed to get something sticky (like soda) in your notebook or cell phone, it will probably need to be cleaned after it dries. That means opening the affected device and swabbing it with a Q-Tip dipped in 99 percent rubbing alcohol--otherwise the electronics are likely to short-circuit from the goo trapped inside.

How to Avoid It Next Time:
Unless you drink from a sippy cup, avoiding spills is hard to do. Some gadgets have waterproofing technologies available: Spill-proof keyboards (or plastic covers) are now commonplace, and underwater camera housings can help if you're shooting pics near the beach or on a boat. If you're going to be near water, even just storing your cell phone or iPod in a plastic bag can save lots of headache later (see "Five Ways to Safeguard Your Digital Camera" for more on keeping your camera safe from the elements).

Problem: You're inundated with pop-ups when you boot your PC.
Likely Cause: Spyware or adware.
The Fix: This problem may not be pretty, but most cases aren't terminal. Here's how to recover:

1. Unplug your PC from the network (or disable your wireless connection).

2. Boot in Safe Mode by pressing the key you're prompted to during boot-up (often <F8>).

3. Run a complete system scan using your antivirus software. Then run both Ad-Aware and Spybot, and fix all the problems these antispyware apps uncover. Restore your Net connection, reboot, and run both programs again after updating them with the latest definitions. Also consider using an online virus checker, such as one from Symantec. (See Privacy Watch for cross-checking online virus scanning services.)

4. If you have a truly nasty infection, chances are the prior step helped but didn't fully solve your problem. (And some spyware can even wreak havoc in Safe Mode, preventing antispyware apps from running.) HijackThis is your next step: It's a specialized application for determining exactly what's trying to gain control over your PC. HijackThis produces a log file that you'll probably find to be gibberish. Post it online at one of the forums listed on the HijackThis page. A volunteer adviser will offer help on cleaning up your specific infection, usually within 24 to 72 hours. If you're in a rush, get an automated analysis of your HijackThis log (you may still need a person to tell you which specific tools to use on your PC). (Also, see our slide show on using HijackThis.)

5. If all else fails, try using System Restore to roll back your OS. If that doesn't work, you'll probably need to reinstall Windows. But exercising patience when going through the prior step and following advisers' tips is almost always successful.

How to Avoid It Next Time:
Use common sense. Don't click on strange attachments, pop-ups, or links on dicey sites. Raise IE's security settings (go to Tools, Internet Options, Security) or switch browsers. Keep your antivirus and antispyware programs up-to-date. Turn on System Restore. Disinfect your PC at the first sign of trouble (spyware tends to snowball). And save current copies of your security apps on a thumb drive or CD for easy access.

Problem: You deleted a critical file, and you have no backup.
Likely Cause: Not enough sleep.
The Fix: Most Windows users know that deleting a file doesn't really erase it. There's a good chance it's recoverable, even if it's no longer in the Recycle Bin.

1. First step: Immediately stop using the PC in question. Close all open programs and stop any real-time indexing services such as X1, Google Desktop, or Windows' own indexing service, as they could overwrite the file you're trying to recover.

2. Give one of the popular undelete products a spin. QueTek's File Scavenger ($49) or Diskeeper's Undelete ($30) are affordable and can make quick work of scouring your drive for deleted files.

3. If an undelete tool doesn't work, start thinking about alternate places where the file might live. Did you e-mail it to someone? Check the sent items in your e-mail client, or ask the recipient to send it back to you. Was the file a photo or video? Check your camera's memory card, or perhaps you uploaded it to Flickr or YouTube. Many files exist in temp folders scattered around your hard drive.

4. With certain versions of Vista, you can use the Shadow Copy feature (on by default) to restore your files. Right-click the folder where your file was, and select Restore previous versions to retrieve your documents (see the Windows Tips column, "Work Smarter With Vista's New Productivity Tools" for more details).

How to Avoid It Next Time:
Nightly backups (or better yet, real-time backups) will make this problem a thing of the past. Also, once installed, programs like Undelete keep track of erased files until they are overwritten, and so make recovering them much easier.

Problem: Your trusty hard drive has crashed.
Likely Cause: Whether it was dropped, became overheated, or simply died of old age, the hard drive is possibly the most failure-prone part of your computer.
The Fix: If you've traced a problem to your hard drive, the solution depends on the specific symptom it's exhibiting.

If the drive spins up but behaves erratically, you probably have data corruption caused by a failing drive. Try the following steps to recover your data and copy it to a good drive before the bad one dies.

Before anything else, if you're using an IDE drive, check that your data cable is connected properly, and if it is, switch to a new cable. IDE cables are notoriously cheap and prone to having their insulation stripped by the metal edges inside a PC case, shorting the cable.
Try booting with a Knoppix CD (as mentioned in our first problem, "Your computer won't boot") or another boot disk to learn if the drive is readable. If it is, back up the data to another drive and reformat the original disk to see if it is salvageable.
You may have bad sectors; try using HDD Regenerator to locate any. Download the demo and burn it to a bootable CD. If the free demo finds bad sectors, it's probably worth paying the $60 for a full version of the software to recover the bad sectors and make the drive usable.
TackTech's Web site features manufacturer-specific utilities for virtually any hard drive vendor. Find out what company made the drive that's failing, then download the appropriate diagnostic application. All of the tools are free and can be of major help in diagnosing problems on a drive and repairing them. (Of these tools, those for Hitachi, Western Digital, and Seagate drives--in that order--will best work on other makers' drives, at least in part, so give any of them a whirl.)
If you still can't get the drive to boot, turn to data-recovery software to attempt to salvage lost files. You have dozens of alternatives in this market, and prices generally run $40 to $200. QueTek's File Scavenger (see the preceding tip on file recovery) and the Stellar Phoenix line (pricing varies) are both worthwhile.
If the hard drive will not spin up at all, you can still try a few tricks to revive it. The following are all last-ditch efforts with only a slim chance of working--but if your drive won't even spin, it probably won't hurt to try. Don't do anything to further damage the disc, as a drive-recovery service might be able to help, too (more on this below). For example, don't tap or beat on the drive, and don't remove the cover from it and expose the heads. Such methods probably won't help and will probably cause data loss.

1. Hold the drive in your hand and rotate your arm outward quickly, parallel to the orientation of the platters (like throwing a Frisbee). Repeat several times. Make sure not to bang the disk on anything. This action is designed to solve a problem called "stiction" (static friction), which can prevent drive platters from spinning.

2. Try attaching the drive to a high-wattage power supply. Even though it won't draw extra power, a burst of juice from the highest-wattage power supply you find could jar it into spinning up one last time. I've seen this work.

3. The "freezer trick" is an old standby if you have a drive that is "clicking" but not spinning: Put the drive in a plastic freezer bag (and wrap it in a paper towel for extra protection against moisture) to keep water out, and then freeze it for a few hours. Let it thaw back to room temperature after you take it out, and get rid of any condensation you see. There's no agreed-upon length of time to freeze it, but start with an hour and work your way up to 24 hours to see if you can make the drive spin up one last time.

4. Remember that if you do get a dead drive spinning, don't let it stop until you've copied all your critical data. Chances are you won't have it working again.

5. If all else fails and you absolutely need data off the hard drive, your last, best hope is to send it to a data-recovery service like DriveSavers. It isn't cheap--expect to pay up to $3000--but I've seen the magic its wizards can do when consumer-grade tools fail.

How to Avoid It Next Time:
Make sure backups are up-to-date. For added security, mirror a second hard drive to ensure you have a real-time backup with minimal risk of data loss and downtime. A cheaper aid: Monitor your drive's health with the free HDD Health utility, which uses SMART technology to predict impending crashes (though it won't catch them all). (You may need to scroll down the linked page a little bit to see HDD Health.)

Problem: You can't get into Windows because you forgot your password.
Likely Cause: Consult your family physician for a complete diagnosis.
The Fix: With each version of Windows, recovering a lost password becomes a bit harder, thanks to Microsoft's inexorable security improvements. However, there's no need to abandon hope.

1. If it's your Windows XP log-in password, try logging in under another account with administrator privileges. (There may have been an account like 'Owner' installed, often with no password, when you first bought your PC.) Any administrator account can reset the password of any other account. If you're not using the Windows XP log-in screen (the one with the icons for each user), you can try logging in with the account named 'Administrator', which is hidden on the XP log-in screen. If you are using the XP log-in screen, try pressing <Ctrl>-<Alt>-<Delete> to reach the old, NT-style screen, which should allow you to type in the user name.

2. If no other account exists on the PC, you'll need to turn to third-party tools to reset the password or crack it. Ophcrack is the first third-party tool I'd recommend to recover a lost password: Using another PC, download the free software from ophcrack.sourceforge.net and burn it to a disc. Boot from this CD and watch Ophcrack go to work. Based on extensive password tables, it can recover most passwords in a matter of minutes, for all the accounts on a PC.

3. You also can try a tool that can reset your password if everything else has failed; note, though, that such tools generally involve a small risk of data loss or corruption. Offline NT Password & Registry Editor and Emergency Boot CD are both free, include bootable CD versions, and are fairly self-explanatory if you're comfortable working with the command line. Both can reset your Windows password for you, and they support multiple versions of Windows.

4. If you lost a BIOS-level password, you can try resetting or bypassing it. First, try backdoor passwords as listed at Tech FAQ. If none works, try resetting your CMOS--as discussed in "Problem: Your computer won't boot"--to cause the BIOS to reset to its default state. Replace the battery and then restore the jumper to its original position and reboot your system.

How to Avoid It Next Time:
If password loss is a frequent problem, consider writing them down and keeping them in your wallet, or storing them in a bank safe deposit box or a safe at home--just make sure you don't lose the key.