Ah, it's an external drive. It's possible that the enclosure is failing. If you are able, try removing the drive from the enclosure and attaching it to your motherboard (hopefully this isn't a laptop). If it works then, then the enclosure is faulty.
Short of trying a different USB cable, none. All the elctronics and the drive are contained within the enclosure. If you can't eliminate the enclosure as being damged or not, then there is no way to tell if the drive is the problem. If the electronics in the enclosure can't communicate with the drive or computer, then no data can make it to the drive.