1. Your PC Won't Boot
If turning on your PC doesn't bring you into Windows, try booting from a Windows 7 DVD or a recovery disc.
You may already have the DVD. If Windows 7 didn't come with your computer but you installed it yourself, you have the disc. If you don't have it, you can borrow someone else's disc.
Alternatively you can borrow someone else's Windows 7 computer and use it to create a System Repair Disc (you can also do this on your own PC before it has a problem). To create the disc, click Start, type system repair, select Create a System Repair Disc, and follow the prompts.
If your computer won't boot from the CD, go into its setup screen and change the boot order so that the optical or CD/DVD drive comes before the hard drive. I can't tell you exactly how to do this since it differs from one PC to another. When you first turn on the computer, look for an on-screen message telling you to press a particular key 'for setup'.
If your PC fails before you can enter setup or boot from a CD, you have a hardware problem. If you're not comfortable working inside a PC, take it to a professional.
But let's assume that the CD boots. When it does, follow the prompts. Likely the utility will tell you very soon that there's a problem, and it will ask if you want to fix the problem. You do.
If it doesn't ask you, or if the disc can't fix the issue, you'll see a menu with various options. Startup Repair and System Restore are both worth trying.
2. You Can't Access the Hard Drive
If Windows can't boot because the PC can't read the hard drive, none of the solutions above will work. But that's not the worst of it: Unless you have a very up-to-date backup(and shame on you if you don't), all of your files are locked away on a possibly dead hard drive. Secondary drives you don't boot off of, both internal and external, also can die with important data locked away on them.
If the drive is making noises that you've never heard before, shut off the PC immediately. In that case you have only one possible solution, and it's expensive: Send the drive to a data-retrieval service. Drivesavers and Kroll Ontrack are the best known, although they're not necessarily better than smaller, cheaper companies. Expect to pay hundreds or even thousands of dollars. If your drive sounds okay, however, you may be able to recover the files for only $70 with GetData's Recover My Files.
If the sick drive is the one you use to boot Windows, you'll have to remove it from the PC and access it on another computer. You can do so by making it a secondary drive in a desktop PC, or by using a SATA-USB adapter such as the Bytecc USB 2.0 to IDE/SATA Adapter Kit.
The free, demo version of Recover My Files will show you which files can be recovered (almost all of them, when I tested it) and even display their contents. Once you've paid the $70 license fee, the program can copy the files to another drive. If that doesn't work, you'll need to use a retrieval service.
3. Blue Screens of Death Attack Your PC Regularly
One second you're working productively, the next you're staring at a blue screen filled with meaningless white text. If it happens occasionally, you curse, reboot, and get on with your work. If it happens regularly, you have a problem that needs fixing.
Windows 7 keeps logs of these "Stop Errors." (That's Microsoft's term; everyone else calls them "Blue Screens of Death," or BSoDs.) To view the logs and make sense of them, download and run BlueScreenView, a free, portable program by NirSoft (portable means you don't have to install it). The program shows you what drivers were running at the time of the crash, and highlights the likeliest suspects. If the same drivers come up from multiple crashes, you should definitely update them.
Speaking of updating drivers, you should make sure that all of them are current. SlimWare Utilities' free SlimDrivers makes this chore remarkably easy, as it scans Windows and lists which drivers need to be updated. If you register (that's free, too), it will find the drivers and run the update for you. It even offers to create a restore point before each update. Don't update all of your drivers at once, however; if you do, and one of them makes things worse, you'll have a tough time figuring out which one.
Frequent BSoDs can also be a sign of hardware problems, especially bad RAM. Although Windows 7 has its own memory-diagnostics program, I prefer the free Memtest86+, which you have to boot separately. You can download the program either as an .iso file--from which you can create a bootable CD--or as an .exe file that will install the program and its bootable operating system onto a flash drive.
4. No One Has the PC's Administrator Password
If the wrong person leaves your company in a huff, one or more PCs could be left stranded. With no one in the company knowing the password to an administrator-level account, you can't install software, change important settings, or possibly access encrypted data.
Fortunately, you can remove the password, letting you log on to that account. You do that with the Offline NT Password & Registry Editor, a bootable, text-based free program that you download as an .iso file. Double-click that file, and Windows 7 will start the process of burning it to a CD.
Boot the CD and follow these instructions. I've put the on-screen prompts in italics. After you type your answer, press Enter.
boot: Just press Enter.
Select: : Above the prompt you'll see a list of hard-drive partitions. Select the right one by typing that number.
What is the path to the registry directory?...: The default is probably correct. Just press Enter.
What to do?  ->: 1
or simply enter the username...: Type the name of the administrator account. If you're not sure what it is, all of the account names are listed above the prompt.
Select: [q] >: 1
Select: ! - quit...: !
What to do : q
About to write file(s) back...: y
New run? [n]: n
# Remove the CD and reboot.
You should now be able to log on to the administrator account without a password. For security purposes, don't forget to create a new password for the account. Just be sure toremember what it is.
5. You Think Your PC Is Infected
Is your computer behaving oddly, slowing down at the wrong time, or refusing to run certain programs? It could be infected with malware. What can you do about that?
If your regular antivirus program--the one you already have up and running--hasn't stopped the questionable software, it probably can't. What you need is a second opinion--and possibly a third and a fourth.
Start with the free version of Malwarebytes Anti-Malware, a utility with an exceptional record of finding and removing malware. Download it, install it, launch it, update the database, and then perform a full scan.
Since installing and updating a cleaning utility are tasks that the infection may interfere with, it's a good idea to follow your Malwarebytes scan with other scans that don't require an installation or even an update.
On someone else's PC, download SuperAntiSpyware Portable and copy it to a flash drive. Boot the infected PC into Safe Mode, plug in the flash drive, and run the program. Since SuperAntiSpyware.com updates the portable program every day or two, you don't need to update it before the scan.
For a fourth opinion, try the F-Secure Rescue CD. This is another .iso file from which you can burn a bootable CD. Just boot from the CD and run the scan. The program will try to update its database over the Internet. If it can't, you can download an update on another PC, put it on a flash drive, and keep that plugged in while running F-Secure on the infected PC.
6. An Important File Disappears
You've been working on a report for six weeks. You have to give the speech tomorrow. The PowerPoint presentation is beautiful. It's perfect. It's...where is it?
Maybe you just moved it to another folder. Click the Start menu, type the file's name, and see what turns up.
Nothing? Maybe you've renamed it accidentally. Click Start, type a word that's in the presentation but not in many other files, and see if that gets better results. If it pulls up a lot of results, click See more results so that you can sort the found files by date.
No luck? Try the Recycle Bin. Maybe you deleted the file.
Dead end? Don't panic. You can always restore the file from the backup you made yesterday.
You don't back up? I bet you will now. As for the file you desperately need to find today, you'll have to use file-recovery software. Before I discuss specific programs, I need to lay down one absolute rule about using them: Until you've either recovered the file or given up, do not write to your hard drive. Every time you do so, you lower the odds of successfully retrieving the lost file.
Following this rule requires you to use portable file-recovery software. Download the utility on another PC and save it to a flash drive. Plug that drive into your PC, and launch the program from there.
The rule also means that you shouldn't restore your file to its original location. Save it to the flash drive, as well.
With luck, either of the following two utilities will be able to find and recover your missing file. First, try the free Recuva Portable. It's fast and simple, it can preview image formats, and it works reliably most of the time.
If that doesn't work, try Software Shelf's File-Rescue Plus. It costs $40, but you can recover up to five files with the free demo version. Strictly speaking, File-Rescue Plus isn't portable, but you have a work-around. Install it onto another computer, and then copy the program file, FileRescuePlus.exe, to your flash drive. After you pay the $40, use Notepad to create a file called key.ini containing nothing but the license key that Software Shelf sent you after you bought the program. Place key.ini on the flash drive, in the same folder as the program file.
Lost files and other disasters happen. You can take all the proper precautions, and something could still go horribly wrong, plunging you into a Windows nightmare. But follow these tips, and you should enjoy some sweet dreams.