digital audio player problem with v3t

Alright, so I bought a v3t from t-mobile a couple of days ago. It was working fine until now. The problem is that every time i open the digital audio player the first time it works perfectly, but then i when i close digital audio player and reopen digital audio player all of my songs fail to play. Thats hard to understand so its kinda like this:

1. I turn on v3t, open digital audio player, then listen to music.
2. Close the digital audio player to make a call.
3. Open the digital audio player again, but all of my music fails to play.

So why does keep happening, and how should I fix it?

Thanks.

Does anyone know?

thanks

howd u get ur music on ur phone?