That dosen't sound good, and it sounds like you're unlucky enough to have had two different failure modes at once.
The drive not being detected indicates there's an issue with either the cable or the logic board. Considering that you've tried a USB adaptor, we may be able to rule out the cable. The 'brains' of your HDD seem to have fried. I had one of those infamous segates which first started erroring out (did yours?) then dying.
The clicking is the dreaded click of death - thats your hard drive trying to recover from errors. Since the hard drive isn't detected, this might also be related to the other issue, but might also mean physical head damage. If the drive is under warranty, I strongly recommend RMAing it. There's very little you can do.