Make sure you try a restart or a reset
If that does not help, and if it is recognized by iTunes when connected (it appears in the sidebar under DEVICES), you can try doing a Restore on the iPod. The Restore button is on the iPod's Summary screen in iTunes. This will erase the iPod, reinstall its software, and set it to default settings. If the cause is a software issue, and there are no hardware-related issues, the Restore should put it back to the original condition.