How do I discover what music file isn't working?

I have all my music in a single folder (not in individual folders for artist and album, they’re really all loose in there).

Right now I have 16,846 songs in that folder but I’ve got 16,847 on my iTunes. My question is, what is the easiest way to find out which one is missing or not working?

I’m sure that I haven’t got any songs playing from my desktop or any other location, so that means that one of them must have one of those exclamation marks when the original file cannot be found.

How can I solve this? I think I read a similar question like this once, saying one could solve this problem with the help of playlists… Any ideas?

Thanks in advance!