When I try to use the camera on my phone, the screen goes black and an error pops up. How do I fix this? Are there...

Your volume setting might be too low or turned off. Turn up the volume by pressing the volume adjustment button on the side of the phone during a call. If that doesn't work you may have a faulty earpiece speaker and in that case you would need to replace it. Check out the Droid Turbo 2 troubleshooting page for more help.