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 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. Windows users having trouble with their iPods should locate a Mac user. We've found that in many cases when an iPod won't show up on a PC that it will show up on the Mac. Then it can be restored. When the PC user returns to his computer the iPod will be recognized by the PC, reformatted for the PC, and usable again. By the way, it works in reverse too. A Mac user often can get his iPod back by connecting it to a PC and restoring it.
8. Try to do an Erase (Disk Utility) on a Mac computer or a format with a PC (Disk Management tool) but ensure you choose the right Drive (your iPod not your Hard Disk of your computer). You may need to plug and unplug your iPod with the computer for several attempts, and switching around Format and Restore, and hope out of sudden, it will get recognized.
9. Diagnostic mode solution – which I copied from a thread of a post from thinktwice
“Then I cam across this special Diganostics Mode that you can get to by resetting and then while the Apple is showing pressing the Select and backwards keys simultaneously. It bring up and weird Diagnostic utility witha a abunch of tests. Here is what I did
- I tried the 5in1 test and got and error on Firewire.
- I did the HDD R/W and surprisingly it passed.
- I went on to the HDD scan. This supposedly tkaes acouple of minute so I waited. I think 4-5 dots appeared then nothing. The iPod started to get hot. THe disk was spinning away. After a while the battery got very low. THis test chews up the battery. So I escaped out by resetting and went to connect it to a power source.
My USB was dangling out of my computer and I was too lazy to get the Firewire AC adapter thing going so I connected expecting the whole lockup thing with iTunes. Surprise. IT was recognized immediately and has been working like a champ. So go figure.
Details on Diag mode can be found at
http://www.methodshop.com/mp3/ipodsupport/diagnosticmode/index.shtml
10.Let me ask you a question, if an iPod with no iPod software with it. When your connect it with a computer, what would happen?
Yeah, the computer will treat it as a fresh external hard disk, which will get force mounted, the computer will ask you to format the iPod. It does not really matter the format is completed or not, the key is to erase (or partly) the corrupted iPod software on the iPod, after that the computer will recognize it.
Once it has been completed, eject your iPod, open the iPod updater and interestingly, you will able to do the Restore this time.
Base on the above, that's why I suggest Windows users who experience trouble with their iPods should locate a Mac machine or vice versa. PC computer will not recognize a Mac formatted iPod, but it will get mounted in an attempt to format your iPod.
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.
I have just read an interesting solution about the Sad iPod, it does make sense but the warranty will be waived once you open the iPod, I would not do it myself as I am not good on doing this
http://discussions.apple.com/thread.jspa?threadID=412033&tstart=0
Pictures and instructions of how to open the iPod case for battery replacement
http://www.kokopellimusic.us/KM_instructions.htm