iPhone 6 video recording without sound.

Hi, I have an iPhone 6 and I'm using the iPhone for more than 1 week, everything was fine until I decide to make a video, the video recording was fine but without THE AUDIO, so I tried to record a voice memo and everything well, all the calls well, dictation to siri well, but video without sound even if I made the video with snapchat still without SOUND !!!! i don't know if is a software problem or what, I have the Macbook Air, almost all the iphones, ipad and ipod and is the first time I'm dealing with a problem like this. I hope you can solve this...

Jorge Montaño Ugarte