[mac7man]

My computer froze so I restarted it. It did not accept my password and asked for my master password. I entered it and then the hard drive disappeared. When I put the startup disk in it can not find anything to repair or fix. If I take out the disk the computer brings up an envelop with a question mark on it. What should I do.

[Sherman Homan]

Well that sucks. If Disk Utility on the install disk doesn't see the drive, then you need a new one. Go here:
iFixit: iPod, iBook, & PowerBook Parts and Accessories
How is your backup?

[Cold Warrior]

Boot from the OS X install/restore DVD/CD and run Disk Utility (it's available as a menu item in one of the main menus at the install/restore interface after booting from the disc). Run the repair drive option to see if it can diagnose and repair damage.

Your HD could have failed.