Were you using MPad? I had a very similar problem. My iPad just stopped recognizing all of the files. I would open MPad and it would be blank. I tried everything I could think of, looked through countless forums, reset the iPad, tried to rebuild playlists, reinstall MPaD... Finally I gave up and just installed MPaD on my iPhone. I used it on the iPhone and it worked flawlessly, but I could not get it to recognize any files on the iPad. I would sporadically check the iPad and about a month later all the files just magically appeared again. It has worked flawlessly on my iPad ever since then. I have no idea where they went, or how they came back.
