Does iTunes see the iPod? If it does not see it:
See
iOS: Device not recognized in iTunes for Windows
- I would start with
Removing and Reinstalling iTunes, QuickTime, and other software components for Windows XP
or
Removing and reinstalling iTunes and other software components for Windows Vista, Windows 7, or Windows 8
However, after your remove the Apple software components also remove the iCloud Control Panel via Windows Programs and Features app in the Window Control Panel. Then reinstall all the Apple software components
- Then do the other actions of:
iOS: Device not recognized in iTunes for Windows
paying special attention to item #5
- New cable and different USB port
- Run this and see if the results help with determine the cause
iTunes for Windows: Device Sync Tests
Also see:
iPod not recognised by windows iTunes
Troubleshooting issues with iTunes for Windows updates
- Try on another computer to help determine if computer or iPod problem
Otherwise
Backup and restore from backup. See:
iOS: Back up and restore your iOS device with iCloud or iTunes