Reseting playlists

I found that whenever I renamed a file that my playlists are all screwed up. I went the stupid route and just put all my music and playlists on my iPod before I named the files consistantly and tagged them all. Now my playlists are all screwed up. All the songs that I renamed suddenly disappeared from my playlists. All I did was remake all my playlists and then resynced the iPod with the option to delete songs on the iPod not in the sync folder in the ON position. Now they all work. Hope that helps!