Okay this is what happened, all of a sudden I went to go into my backup drive (D

on my computer. It's where I keep everything important, such as pictures, program installs, music, videos.... etc, and it wasnt there, i restarted and checked the BIOS, finding that it was still recognized. I tried to restart and access it with no luck, restarting again I entered the BIOS, finding that it wasn't recognized now. I checked inside the case, and the 4 pin molex, and the ribbon cable were fine. Any ideas?