Suggestions when you run into a problem of a Sad iPod icon or a folder icon with exclamation point with your iPod.
1. Try these five steps (known as the five Rs) will conquer most iPod issues.
http://www.apple.com/support/ipod/five_rs/
2. Try to put the iPod into Disk Mode if it fails to appear on the desktop
http://docs.info.apple.com/article.html?artnum=93651
Still can't see your iPod?
Several things could keep iPod from appearing in iTunes or in the Desktop/Finder when you connect it to your PC/Mac. The most likely causes are listed below in logical order. Check each one starting from the top of the list to see if that is what's keeping iPod from appearing.
3. Try to wait 30 minutes while iPod is charging.
4. Try another known-good FireWire or USB through Dock Connector cable.
5. Try another known-good FireWire or USB port on your computer .
6. Try to disconnect all devices from your computer's FireWire and USB ports.
7. Try to connect on a different computer i.e. a PC formatted iPod connect with a Mac computer or Mac formatted iPod with a Window base PC.
8. Try to do a Erase (Disk Utility) on a Mac computer or a reformat with a PC (Disk Management tool) but ensure you choose the right Drive (your iPod not your Hard Disk of your computer).
If one of the above step helps to get your iPod to be recognized with your computer, do a Restore.
But, if none of these steps address the issue, your iPod may need to be repaired. You can arrange for service at the iPod Service Website.
If you still cant solve the problem, please post here again