Depending on certain things, go into your BIOS or setup (normally press Delete when its testing your RAM) and do a low-level format. However:
1. Make sure you have a bootup disk with fdisk, format, and command.com
2. A lowlevel format can permanantly crash your hard drive when done incorrectly, so if you're uncomfortable with that, just go with fdisk and then format, but sometimes you'll NEED to lowlevel it first. To tell, was your hard drive compressed when it crashed? If it was, then you have to low level.