Computer not recognizing USB ports

My screen name says it all: USBereft. All my USB ports worked fine until one day last week when I accidentally disconnected my daughter's iPod Shuffle while it was downloading music from our hard drive. Now the computer does not recognize anything plugged into any USB port--not the camera, the iPod, a flash drive, etc.

 

I have chatted four different times with Dell online support techs. We have checked to be sure the USB ports are working through a diagnostic test, and the report was fine. We have uninstalled all the ports and allowed them to reinstall themselves. I have uninstalled and reinstalled the iPod software. Finally, out of desperation, I performed not one but TWO restores to take my system back to a time when it was working. Nothing has worked so far.

 

I am completely frustrated and would appreciate any advice anyone out there might have.

 

Thanks,

USBereft