Are you using the ports on the front of the computer or on the back of the computer.
If you are using the ones on the front, try plug the USB drive into the back of the computer, if this works then we can say it is the connection between USB ports on the front of the computer to the motherboard.
If you have already tried the back and still have no luck, boot the computer with a linux disk (http://www.ubuntu.com/GetUbuntu/download). Ubuntu is a popular and easy to use linux version and then try the same thing again.
If this does not recognise the device then I can safely say that the Hardware may be at fault and a new USB controller will need to be purchased.
Also some other questions to think about:
1. Does the USB Device work in any other computer?
2. Does any other USB Device work in this computer in question.