Usb ports do not work..

I have a HP nc6000 XP home service pack 3....i had service pack 2 but i installed the 3rd one...for about 2 weeks my USB ports worked fine...and now when i plug something in nothing happens at all...i also have a cooling pad that plugs into the USB port and starts 2 fans underneath, this usually worked after everything else i pluged in stoped working, but now there is not even power comming from them and i have no idea what to do...i tried installing all the drivers for this laptop again but nothing worked...can someone help me out???