i have the same problem i have htc one and all of a sudden my phone stopped reading some music files, and every day i would be missing more. i know 100 % it played this songs before and now it cant. it is so frustrating cose i had such good collection of music and now i have to re-download missing fires i tried to update my system but it didn't help, also i was suggested to reboot my phone and what it did is just deleted all the music files that couldn't play, so apparently for some reason it becomes temp files which is odd, why does it do that, i never had this problem with my other phones, does any one have the answer to that? how do i get my music back or at least i dont want to keep on missing my music files, please help