@theautisticgamer The reason the Past music works is because it's PCM audio (part of the game code), whereas the rest of the game's music is RedBook audio (meaning it's streamed from the CD). Check your .cue file in Notepad or some other text editor, and make sure that your files are named exactly as they appear in the .cue file. It might require the audio be in .WAV format instead of .MP3 format. And if you're trying to run the game from the .iso file, use the .cue file.
Please do not post a support request without first reading and following the advice in https://retropie.org.uk/forum/topic/3/read-this-first