revert to itunes 10.7- recovering recently added songs/playlists

I reinstalled 10.7 and used the previous library as per the instructions here https://discussions.apple.com/thread/4559563?start=15&tstart=0, and didn't have any trouble getting the old version to work...however, I lost all the songs and playlists that had been added after that library was created, which was several months ago. Is there any way to get those back? The songs can be manually added again, but it would be difficult because they're sorted in the music folder and I don't know which were new since then. Thanks in advance for your help!