I've had that problem myself. I keep a copy of the stock rom in my PC. Hook up your phone to your computer. Once you download the stock rom, (I found mine on Google Play) run the file thru extraction. open it up to the file marked SYSTEM. open that up and find the file marked APPS. open that up and it will show you all the "stock" system apps or apks. Find the Camera apk and send it to your sd card. Confirm it's in the sd card & unhook your phone from your computer. Then open up the file using your file manager and it will run thru a regular install program. Once installed move that camera apk to a file marked backups for storage. (if you have one already, move it to downloads or some place safe for future use.) Make sure you have a copy of that stock rom before you uninstall ANY SYSTEM APK. Once you do the install, run you camcorder to do a sound check. you should find it working again. I lost the sound of part my granddaughter's 2nd birthday party video because of this issue. Keep that camera apk handy. And do a sound check before important events.