My WD portable HD fell off the desk onto the floor. It installs the device drivers (takes a little longer than I seem to recall) but both computers I have now won't recognize the drive in Windows Explorer. When I plug the drive in there is a brief buzzing sound before the drivers install but that stops, just can't see the drive in Explorer. Any ideas or help is appreciated.

Sorry to say drives are not designed to withstand such a drop. I'm afraid it's now a paperweight.

You could buy an external enclosure your drive can be installed in (that supports EIDE or SATA drives, depending on which type of hard drive you have, or both types), install the hard drive that's inside your external drive into that, and see if that new external drive combo works, but the chances are, since your external drive is "portable" which indicates the hard drive inside it is laptop sized - 2.5" - the hard drive is relatively delicate and it is probably damaged.