A clicking HDD is a Failed or Failing HDD.then there is a clicking sound.... The drive is 6 years old
This probably wont' help, but you can remove the HDD from the enclosure and attach it internally to a desktop computer as a secondary drive.If the drive is recognized in the Bios, then you can run Data Recovery software on it, like Spinrite. I have had the best luck with GetDataBack. If the drive still clicks and powers down, then it needs to be replaced.
Always have files you can't live without backed up to more then one place.