sound goes in and out

i don't use headphones because i have a touch with a speaker, i have a classic to use with headphones.
i can be doing anything and have sound.. music, movies, apps, whatever... then out of nowhere i can pick it back up and the volume keys do nothing, music doesnt have a volume bar, and videos don't either. i can go to the sound settings and the volume bar can be put to max, i exit and still no sound then randomly the sound will come back and the volume keys work. i try turning it off and on and sometimes it works, other times it doesn't. it seems to go in and out randomly there is no constant the battery could be fully charged and the osund will stop anyone know what's going on?