Might be needed drivers. Have you looked in device manager for the USB controller status? If the controller isn't listed go to CMOS setup and enable USB.
normally when i plug something into a usb port, it recognizes it as new hardware and all i have to do is load the drivers and its good to go. but after my last format, its not recognizing anything i plug into the port. the power goes on on the devices. i need my usb for my wireless internet, and i have formatted 4 times, each time all i had to do was plug the devices in, and instantly i would here the new hardware sound, now nothing.