First of all do not paly with original sound files in the Music maker always use copies.
If you remember which files you had moved go and open the folder and see files can you locate any file other than audio file. Audio files could be wave, mp3 Ogg. If there are non audio file and you do not need delete them or if you are not sure move them or backup some where.
After doing this clear internet history and cookies. Start Music maker and see if that solve your problem.