it might be because you didn't turn the volume up.. if not then maybe you should ask sandisk to fix it
Ok I Updated my firmware for this mp3 play and i insert headphones and nothing comes out. Its not the head phones because i check them. I Had this problem before but when i turned it off and back on it began to work again. Any idea's What to do Thanks in Advanced.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic