Can you check how much capacity is used up in your iPOD? If it shows that there is some space that is used in the iPOD for your music then it can be that your DB is corrupt.
It above is that case then it doesn't sound like your iPod is broken, but it can dump the db for no readily apparent reason at which point the data is still there but invisible to iTunes & the iPod. It's probably too late now, but sometimes there is a backup copy of the database that can be replaced. The database is at iPod_ControliTunesiTunesDB and the backup, if there is one, is at iPod_ControliTunesiT.tmp. You can prepare for a future crash however...
First goto the preferences menu and check *Disable automatic syncing of all iPones & iPods* , then with the iPod connected goto the iPod summary tab and uncheck *Open iTunes when this iPod is connected* . Now, when your iPod is behaving, you can connect it to your computer & backup the contents of iPod_ControliTunes to another folder on the iPod, e.g. backupiTunes , before making any changes. If the iPod should crash when you update it you should be able to restore the iTunesDB file. Depending on what you added or deleted there might be problems if it tries to play non-existant files but at least you could plan when to do the full restore.