IPhone 4S sound won't work but headphones will?

So I never dropped my phone nor do I usually play straight from the phone always my headphones but in use the ringer for messages and stuff but my sound won't change? I never dropped it in water or anything it was just working then I got a call and after thy it stopped working?

Go to the settings app - Sounds. Try messing with the volume in there, it should fix it.