I cannot hear my music from my media player and the volume is up and on

what sort of mp ? your codecs or drivers must be not complete ?

first make sure power is still geting to any speakers your using because my old speakers stopped working because the cord had been steped on so much it stoped working
to test if its the cord try headphones just to see if sound comes out if it does u need new speakers or a speaker cord
if still nothing try the volume controle at the bottom right hand corner
and not to sound like a jerk but make sure the volume nobe on the speakers are on

you should be sure that:
-the sound-card of you computer
or
-you haven't uinstall codecs
or
-the loodspeackers are damadged
or
-the extention of the music filesare not compatible with the software (like windows-medea player)

make sure Windows Media Player on your PC is 9.0 or higher version