If you are lucky it's just the external box that is bad and the drive inside is OK. First, is there an optional external power supply available for this? If yes, get it and try it with that. If it's only a USB cable, buy one with a dual connection so you can use two USB ports for power. If that fails, crack open the case (if it's out of warranty), remove the drive and either install it directly into a computer or buy a new USB enclosure for it. If the issue is not with the hard-drive, that will get you working.