So today, my computer wouldn't boot up for some reason. I tried to boot from my Windows XP disk, but that didn't work, and it froze after trying to boot from there. After disconnecting the hard drive, it works fine, expect I can't really use my computer without it. Is there any way to fix the hard drive? It's a SATA drive, and it was working fine yesterday, too.

I would set up a CD with UBCD4Win and boot off of it, use one of those scanner programs to see if your harddrive is corrupted, if any large sections are still good, you may be able to save it by partitioning the good sections of it, and leave the bad sections out.

Sounds like something that happened to me, Try replacing the cord to your harddrive with another, if that doesnt work, you might have fried the port on your motherboard like I did D:

Most likely your spindle is broken. That's the most common cause of hard drive failure. Usually you haven't actually lost any data, and computer stores can retrieve the data off them for a price. But before you do that, try the cord like darkling said.

Usually you have ample warning when a hard drive is failing, lots of noise, occasional failures to read that get more frequent.
I would try to stick it in another computer as a slave. If that doesn't work, try to access it from dos.

Okay, it hasn't failed me anytime soon, and it's been working for quite a long time. I'm going to try a different cable, see if that works. I'll get back to you guys in a bit.