@GooglePlayMusic won't update my library... I have deleted cache and date countless times and still nothing. The problem began when I moved the songs from my bluetooth folder into my music folder and then the songs disappeared from google play music.
Sorry to hear that, have you tried refreshing your library through Menu > Settings > Refresh? If you've also done this already and it's still the same issue, you can reach out to our support team for further help here: http://yt.be/help/i16t