Why am i not getting any sound when i playback my videos on my iphone 4?

I have a iphone 4 & I've been recording videos on it and after I get done I go to view them and I can't hear anything. I can hear people when they call me or facetime, I can hear my music and youtube videos and app sounds, just not when I playback the videos I record. I just updated it to the ios 7 verison on my iphone. Do you think its causeing it or is something wrong with the camra app? I don't know what could be wrong, help?

Added (1). Tryed that I went to sounds and turned the sound up and stll didn't work

Goto settings and turn up the volume and the set the volume limit.very simple

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