Well you could run the manufacturers diagnostic program on it, but if it actually isn't being seen by the computer at all then that probably won't work. To avoid any windows related problems, I recommend the bootable cd diagnostic. Seagate seatools, Western digital data lifeguard diagnostics, etc. You can get all them on one if you do the ulitmate boot cd, but its a lot bigger download than just a single manufacturers diagnostic. Go ahead and see if the diagnostic sees the drive and go from there. If not then you have problems. It could be the the controller board, which you might be able to swap if you have another of the exact same drive. Even if they appear the same it may or may not work. Other than that if there is serious stuff on there you can't loose you need a professional ($$$$).