LG Ally not playing music! Please Help!?

I've had the LG Ally for a week and a half or so now, and all of the songs were transfered from my old phone via a memory card. This is the first time ive tried to play music on the Ally, and it wont play. No matter what song i pick it will scan thru all of the songs and then stop at the end of the last one, nothing will actually play and there is no sound, not even with headphones. Ive tested the sound on the phone by playing a video on youtube, and i tested the headphones on a computer and they both work, just not for the music. Does anyone know what this is or how to fix it? Please help!!