PC won't recognize ipod

My PC crashed and I had to do a restore. Afterwards, my son's ipod, which had worked perfectly from the beginning, was no longer recognized by the PC. The ipod still plays all the songs - no data was lost on the ipod. But when he plugs it in, a pop-up declares "USB device not recognized." And this happens now when he plugs the ipod into ANY computer, so it seems that something is corrupted on the ipod itself. I have tried a number of things; having the device manager look for drivers, directing the search to c:/windows/inf, copying usbstor from one folder to another, things I read online. I have also tried the reset on the ipod, which does nothing. I would try the restore on the ipod, but I think it has to be recognized in iTunes to do that. The biggest problem for my son is that he can't charge the battery on the ipod. Thanks for your help.