LG Muziq / AX-565 / UX-565
If you can't play the music you loaded on your phone...
It is probably due to the fact that your files are read only.
I loaded a few mp3s under the Music directory. They would show up under Memory Card Manager. However, they would not show up under the Sprint Music Store player.
After disabling the read only option on the offending files, everything works perfectly.
Hope this helps someone...