iTunes sync error 13019

i plugged in my iPod to my computer and iTunes was automatically pulled up. it didn't start syncing but when I checked my iPod later, there was no music anymore (2500 songs) on the device. when the iPod is plugged in, itunes says the iPod is full and you can pull up the songs and even play them but it will not let me sync and won't put all the songs back onto the device. this is not the original computer it used to be synced on but I don't appreciate that iTunes is basically holding all my music hostage and won't allow it back onto the device. please help!! don't want to lose all my music!!