My IPhone 4 doesn't have any sound

I have no sound on my iphone! It works in music but I don't get incoming calls, text messages, no sound on games, and my keyboard clicks don't work either! What is going on please help!

Added (1). All of my ringers are up too and all the mutes and silences are off!

XD I'm writing this on my iPhone. There's a little switch above the volume buttons flip that and the sound will be back.

This helped a lot.