Check in your Device Manager, from the Start -> Run - > devmgmt.msc whether the USB device is listed when you connect it. You can try removing / uninstalling all the USB drivers from there and then scan for hardware changes, so that the drivers are re-installed
At bottom it will have universal serial bus controllers, it usually has an "X" by it if its not working.
If it does right click it and press update driver, maybe the drivers have broken.