Why doesn't my Iphone 4s have sound?

A couple weeks ago, my IPhone stopped having sound, the only time it works is when i'm on the phone with someone or if i have earphones plugged in, when i use the buttons to turn up or down it shows a blank bar, i tried restarting my phone a few times but nothing, i also turned on the assistiveTouch and that doesn't work either. Its not on mute either. Does anyone know?

It's dirt

Same problem with my phone. I have dug deep into settings and every possible setting that I can find is properly set for sounds and notifications. Lost for answers