Alexander: Fixing a PC zapped during a power failure

Q: My daughter's Windows 7 PC was left on during a power outage, and since then we haven't been able to start it up properly. We get the error messages "group policy client service failed the logon" and "access is denied."

I couldn't fix the problem using the repair tools that are available at the "C:" prompt midway through start-up. And I can't reload Windows, because we don't have the original installation disk, although we do have two disks that we made when we got the PC. Is there a solution? If not, can I install a different operating system, such as Linux, on the PC?

Darlin Caro, Destrehan, La.

A: The disks you made when the computer was new probably contain system repair software. Insert one of them in the DVD drive and reboot the PC. If the PC starts up, you should get a menu that includes several options to fix Windows, including self-explanatory "start-up repair," "system restore" (which returns the PC's settings to the way they were on an earlier date), and "memory diagnostic," which will show you if the PC has memory errors.

If that doesn't work, you could buy a new copy of Windows 7 for about $100. All data and programs on the PC would be erased by loading a new copy of Windows.

Alternatively, you could overwrite Windows 7 with Ubuntu, a version of the free Linux operating system. Again, everything on the PC will be erased. If you have access to another PC, go to Ubuntu.com, click the "desktop" tab to download the free Ubuntu, then burn it to a CD disc. If you don't have another PC available, you can buy Ubuntu CD at a computer store for less than $10.

Q: My laptop screen was smashed against something when I took an airline trip, and the screen has at least one major crack in it. I can't access my files because I can't see anything. Can this be repaired?

A: Yes, replacing a cracked laptop screen is one of the most common computer repairs. A computer shop typically charges about $120 for parts and labor. It's your call whether the PC is worth repairing at that price, because you could buy a new laptop for about $300.

You can save money by replacing the screen yourself. Online stores typically sell a laptop screen for $50 to $75 plus shipping (see tinyurl.com/ywenq2 or tinyurl.com/yg5w8l9). You can find step-by-step screen replacement instructions at tinyurl.com/nlyl5lo.

Reminder: Some readers have been unsure how to use the short-form Web addresses used in this column, called TinyURLs. The TinyURLs are nicknames for much longer website addresses. You should type them into the address line of your Web browser, which is the line that tells you which website you are currently visiting. Because TinyURLs aren't real website names, you can't search for them with Google.