Perhaps you have a problem with iTunes and you want to delete it to reinstall.
It is very common to read the forum posts regarding transferring music from an iPod to the iTunes library on a computer. But Apple decided not to allow users of its player to do that simply from iTunes for example.
Perform a reset of the iPod :
1) If you own an iPod 1G, 2G or 3G: Press the Menu and Play / Pause button until the Apple logo appears.
2) If you own an iPod mini, 4G, U2 or photo: press the Menu and Select buttons until the Apple logo appears.
Update the firmware of the iPod :