Hi there j-ar,
I would totally agree with the other guys. The first thing you may want to do is to back up the important data stored on the drive.
After that, you can test it and see what is wrong with it: http://www.tomshardware.co.uk/forum/282651-32-best-diagnostic-testing-utility
Sometimes, external drives could make clicking sounds when there is not enough power supplied to them. This is why, it may be a good idea to attach it with another USB cable. The ports on the back of the computer case tend to provide more power.