Typically when a hard drive dies, it is usually not possible to fix it. However, if it is, it will be much more costly than to buy a new one. Hard drives usually only last a few years (less if external because of heat issues). When they do go, you just buy a new one and chuck the old. (Trust me, I replace about 5-6 hard drives a week.)
Naaah. Generally, the sound he described (called the click of death, FYI) signifies the death of a drive. Data recovery is an expensive proposition, with no guarantee as to how much of it can be recovered. You'll need to go for a new drive and replace from backups. (You did take backups, didn't you?)
like the first guy said, u need to open up the enclosure and take out the hard drive - then plug it into the computer as u would for an internal hard drive. This is the only chance u have to MAYBE save the hard drive. I did it and it worked for me.... but I was lucky. Be prepared to shell out some cash to buy a new hard drive though. good luck.