Somehow I deleted the contents of all my playlists and other files. Can I get them back?

While I was in my ITunes library on my Windows computer, I attempted to delete a Playlist that was "empty". I don't know what I did but now all my playlists are empty along with all my other groupings such as Purchased, Recently Added, Recently Played, and on and on. When I open any one of these now (i.e., a Playlist) it lists how many tunes are in the playlist and shows the total playing time BUT none of the tunes are there. Is there any way I can restore what was accidentally deleted? I have an IPod which was recently synced with the Library and it still has everything. Is there any way I can load the library from my IPod into my ITunes library on my computer? Thanks for any help or suggestions.