Re: Hard Drive Crashed!
Try connecting it to another computer? Whatever you do however, don't re-initialize it. You'll wipe the drive if you do that.
If you can't get the OS to recognize it, try running the drive through a test scanner - some motherboards will allow programs like GWSCAN to see a drive via USB, but if you can take the drive out of the enclosure and connect it directly, that's how I would test it to be absolutely certain.
External hard drives are no better, and in some cases, worse than internal drives. They're exposed to more wear & tear than a drive inside of a PC. I hope everything on the drive is stored elsewhere?