Chosen Solution
I just bought a new iPhone 7plus and already I’m having a problem with volume. I noticed after a couple weeks it stopped sounding text tones, alerts, etc and even keyboard clicks. Even if I go to settings and choose dif sounds for txts and various alerts, the only ones you can hear are the ringtones. Also, my first clue that there was a problem was when I initially went to adjust the volume. I noticed the bottom sound Level bar didn’t even exist. It does however if in phone mode. What the heck apple??
I would hold down the volume key and the power button and start with a soft reset. Then if that doesn’t work restore the phone to its out of the box state, do not restore to backup. If that doesn’t work please take back to the nearest Apple store they will be more than happy to assist you but they will ask you have you done those two things first.
You can also try to reset network settings, believe it or not
