Problem with iphone ringtone hearing?

I'm using iphone 4 version 5.1.1.
it was fine until few days ago but since yesterday,
whenever i get phone calls, i can't hear my ringtone.
My ringtone is a doorbell which is a default ringtone.
I have tried many things like go to setting and adjust all the sound settings and turn off the bluetooth or A2DP.
And i have tried re- setting my phone but it still doesn't work.
I can hear the ringtone through my headset. But i don't use it often so its a problem to me.
Is there any other way i can fix it with out going to the apple store?
I literally tried most of the things i can do.
Please help me with this. Is there any way i can fix this? Or do i have to go to the store?

Unfortunately, I'd say going to an Apple store is your only option right now.