does the iPod shows up in itunes ?
click on the eject sign - any change on the iPod screen ?
if not, try the hard reset, press and hold the menu and select button at the same time until the iPod restarts, while booting up - unplug it from the computer.
i hope this helps
The first thing to try is reseting your iPod. Hold the Menu and Select (center of the click wheel) buttons simultaneously for about 6-10 seconds. The apple logo should appear for a while, and after a little bit it should go to your iPod's main screen.
In general, Apple has 5 R's for troubleshooting your iPod:
Reset, Retry, Restart, Reinstall, and Restore.
For more info, here is Apple's troubleshooting page, as well as [[iPod 5th Generation (Video) Troubleshooting