You know don't you that if you have your iPod & iTunes set to auto update then it will delete all previous songs on the iPod & update them with the present or new playlists on your iTunes. SOunds like you need to load them manually.

If you're a mac user, go to the General Mac OSX section of the forum & look at the Sticky at the top of the list. If you're a windows user, then see the iPod tutorial link in the Sticky at the top of this section.

If I've misunderstood your problem then please say. Go to LW's Library window & select either or both Saved Files & Shared folders & press the Explore button & this will open the folders up for you to check. Do it one by one.