Could be a couple of things, but as the blue light is on the it looks as though it's getting power.
The problem may be with the drive itself, that may have died, it does happen more often than you think. Alternatively it may be that the electronics that have died and the drive is OK , it's just that it can't talk to anything.
First thing is to leave the drive connected, switch it off and then on again and see if anything changes. If it's still not playing ball you could try extracting the hard disk from the drive and fitting it into an external enclosure and see if the works.
If it doesn't work then it looks like the hard drive itself has died. You could then purchase an a new drive and fit it into the case.