I recently updated to 5.1.1 from 5.0.1, and after doing so none of my music would play on my phone. I would go to play a song, and the music app would show the song starting, but the audio would never start and the song would never advance. I tried restarting the phone, and no matter what I couldn't get music to play. So then I decided to do a restore of my phone and let it resync the music and try again. After doing the restore, my phone will absolutely not sync any of my music. I have tried checking and unchecking "Sync only selected songs and videos." No matter what it is set to, I cannot get it to sync any music. It syncs my apps, and then just finishes the sync without copying any music over. My music files are valid, I can play all of the music directly in iTunes. I never had this issue before upgrading to 5.1.1. I also have iTunes match. So, my whole library still shows up but everything is over match. I am able to play music now over match, but I would still like part of my library to reside directly on the phone.