How to fix this internal speaker IPod Touch Problem?

Okay so here is the deal.
The internal speakers in my IPod Touch 4
ARE working. But...
When I go to play any music they don't work.
Also when I press the sound effect button volume it doesnt show anything.
What I'm saying is that they work only for ringtones, text-tones, alerts..etc.
But they don't work for music.
Help?
Also when you are in lock mode and go to play music, The volume option isn't available.

I don't know much about phones but that sounds like a problem with the software that plays the music like a missing codec.

IPod Touch support:
http://www.apple.com/support/ipodtouch/