External hard drive not recognized

I have this Acomdata HD500UHE5-72 500 GB USB 2.0 Hard Drive that I purchased less than a year ago (now that I checked the ratings this unit is at the bottom of the list). Suddenly my computer did not recognize the drive anymore. You can hear the USB sound looking for the device but cannot find it. Power turns on and I use Windows XP SP2.

I have tried opening from a different PC, replacing the USB cable and other tricks in the Computer Manager with no luck.

p.s. I lost my user name and password and had to sign up as a NFG again