My iPod 4G connects to the computer (Windows) but doesn't connect to iTunes. I've restored the iPod but it didn't work.
iOS: Device not recognized in iTunes for Windows
I would start with
Removing and reinstalling iTunes, QuickTime, and other software components for Windows Vista or Windows 7
Removing and Reinstalling iTunes, QuickTime, and other software components for Windows XP
Run this to help if it identifies the cause
iTunes for Windows: Device Sync Tests
Have you tried on another computer to help determine if you have a computer or iPod problem?
Retrieving data ...