My external hard drive is not showing up

[Kurikara]

I'm having quite a problem here. My external hard drive (Astone - 2Tb) isn't showing up on my computer - or anybody else's. I lent it to a friend, and I believe he may have been rough with it (The base is missing 2 screws), and after receiving it back the following day, I plugged it into my laptop. It came up with "Installing device driver software" which is odd, since I've used it on there many times before. Afterward, it would flash in My Computer for a second coloured grey, then disappear. It does not appear in Safety Removal Hardware either. I've tried this on several computers, but with no difference, and the blue light still works. The problem is definitely with the Hard Drive, since thumbdrives still work fine. Reformatting isn't an option, because there are important, irreplaceable files on there. It does, however, show up in control panel > Hardware and Sound > Devices and Printers. I still can't access it though - When I right-click and go to browse files "Removable Disk (D: )" is written in grey. Is there anything you tech geniuses can do to help? I'm really getting desperate here...