Hi,
There are a few reasons this would happen, The options are a bad
USB cable, a faulty driver in your
PC, a failed
circuit board in the enclosure or a failed circuit in the drive itself.
First try the drive on a different
PC and see if it works. If it does reply back and we can look into the failed driver. If it doesn't then take it to your local
PC shop and have the technicians test it with a new USB cable, if it works buy the new cable. If that also fails to work have the technicians move the hard drive into a new enclosure.
If it works in the new enclosure buy the enclosure and your on the way. If it doesn't, then the hard drive itself is the problem. If that is the case you will need the help of a
data recovery pro to retrieve your
data. If this is the case reply with your location(Country, State and City) and I will assist you in finding a reputable pro to assist you.
Hope this helps FixYa,
Chris