Can't upload songs onto my iPod Classic 120GB

Your post suggests that you have had music on this iPod in the past, which leads to the question of why does it not have any now. This may be because:

• • you are syncing the iPod with a different library than before and have not set Sync options for this library
  • the Sync options have been reset (due to unknown reasons)
  • the iPod has failed (although I would expect a message on the iPod's screen if this were the case)

Check the settings for the Sync procedure with this specific iPod:

• Connect the iPod to your iTunes Library
• tap the device icon that appears just below the menu

• this shows the Device/Settings/Summary pane. Switch to Device/Settings/Music (as indicated at 1. in the screenshot below:

• ensure that the Sync Music box (2.) is ticked (checked)
• in the grey area below the Sync Music, choose either:
  • Entire music library - which adds everything in your library that has a tick (check mark) in its box
  • Selected playlists, artists, albums and genres - which then opens up section 4. If you use this option, you must select items in section 4 that will be added to the iPod. If you do not select anything, the iPod will remain empty
• if you had to change any of these settings, tap the Sync (or Apply) button in the lower right corner of iTunes (not shown in the screenshot)