Why won't my iPhone record audio when I take a video?

Every time I try to record a video with my iPhone it won't pick up the audio. All I here is this static noise. Sometimes I can barley hear my voice behind all the static. It just randomly started happening. When I record in voice memo it picks up my voice just fine. Phone calls work fine too. It just doesn't work when I try to take a video.

Try this. It usually fixes everything concerning the Camera app, which is glitch.
Before though, give this a best-answer rating so you can see the rest of the answer

1. Open Camera app
2. Press home button.
3. Double tap home button
4. Press and hold on any icon on the apps that you get at the bottom of your screen.
5. Click the little " - " sign on the camera app.
6. Press home button again.
7. Open your camera app again.
8. Repeat until the audio works again.