Are you using WMP to play them? WMP has a bug with compressed id3 tag headers (it can't read them - unlike most audio players.!) So if you used the LW Describe function on any files, WMP won't be able to read those files.

Not sure why you can't move them back. What you could do is Share that other music folder. Then play them with LW's media player. How to Share Folders (click on link)