Sorry for the caps lock, it always pisses me off to have to read through 5 pages of annoying people going "hey me too" to get any relevant information. Any way:
This is usually caused by the Ipod not recognizing the hard drive. Your hard drive is most likely broken. Go to www.ifixit.com, look up your ipod model in repair guides, and follow the steps to stick a new one in. Or, you can try the dropping method, which involves dropping from a certain height, you'll have to look it up since it might just fix sad face, not the url. But if you use this, it is by no means stable and your hard drive will most likely break again soon, so BACK UP YOUR MUSIC. Or, if you are too lazy to fix it and the drop method wont work, you'll either have to send it in or try to find a local, cheaper repairman. Try craigslist.