What have you tried so far in terms of troubleshooting this issue? Are you plugging the iPod into a high powered USB 2.0 port on the back of your PC? Have you tried a different USB cable?
What happens if you try to reset the device with it still connected to the PC?
Try running an iTunes Device Connectivity test and posting back the results.
Have you carefully worked through each and every single suggestion in this Apple support document?