I have a pretty large music collection that consists of MP4 audio files. There is a program that can play MP4 files, but it can only load MP3 files (go figure), so the entire collection has been renamed to have an MP3 extension. The files have only been renamed, but not modified or converted from MP4 to MP3.
Recently, to try and organize the music, I loaded it into MusicBrainz Picard. Satisfied with the metadata it recommended I hit "save" on impulse and the files now all have correct metadata and album artwork but none of them can play. I'm looking for some way to reverse this and recover my music, but traditional file repair tools don't seem to be able to detect the metadata from one file type in the other. I've tried stripping the MP3 metadata using ffmpeg, but I don't really know what I'm doing and it didn't work.
How can I "untag" my music from MusicBrainz Picard so that it works again?