Did I damage my ipod's software?

As some background, me and my friend both use 20 gig ipods with windows computers. Apple's made it so it's nearly impossible to transfer music from one computer to another, but about 2 weeks ago me and my friend tried to move music from his ipod to my computer by getting it from the F drive instead of the ipod's icon. The music transfered, but it screwed up his ipod, and now he can't play music on it. Mine worked fine for about a week and a half, but a few days ago it stopped responding to the buttons and the clickwheel. But, to make it more complicated, my computer still recognizes it, it could still play music even though i couldn't press the buttons, and it DID reset when i held down the menu and select buttons. I've tried restoring it, but that didn't do anything. So, my question is does anyone know what happened, and is there a way to fix my ipod, and less importantly, my friend's?