Why does my iPod system crash and how can I restore it?

Well, I have a ipod 3G that was restored to it's original IOS version and I locked it with a passcode. Later on I wanted to sync apps from my friend's computer and the message appeared like "This ipod was synced with another computer. Do you restore from backup and continue syncing with this computer." and I clicked continue. The sync was not complete because it had passcode and somehow it crashed. Now I cannot sync it or enter passcode, because the "Enter Passcode" appears but doesn't respond to entries. Neither can I restore it. The wallpaper of the screen is the one that I had set before restoring. Is it possible to reset the ipod firmware. What Can I do. Please Help