My friend has an 80GB IDE ATA133 Hard Drive. One day, his hard drive started making a bunch of clicking noises, and then it doesn't work. He tried disconnecting and reconnecting the cables and such, and it didn't work. About 5 days later, he tried, and he got his computer working. It's slower than ever and still makes clicking noises from the hard drive.

Any opinions/advice?

I don't have too much info but what he told me. Thanks guys.

Advise him to make a backup of all his vital data, then see if the disk is still under warranty, if so, ask for an RMA from the supplier or manufacturer.

Try out the appropriate test-program that you can find in the Sticky (= Read) at the top of this forum.
If that finds no errors, check HDD-Regenerator from www.dposoft.com. Well worth its money.