Why is my iphone4 permanatley silent?

My iphone 4, running on ios 6.0.1 will not turn off silent mode, when i try it the ringer volume doesn't appear, and the sound when i type or receive a text does not work. I have looked on settings on my sound and everythig is switched on so it should work but it doesn't. I can listen to music, and speak over the phone fine. Is my phone broke or is there a way to fix it?

On the side of your phone, where the + and - buttons are (volume control) is another switch. Slide it and see what happens