- For a while, the keys and button presses were making no sound.
- For a while, during phone calls I could hear and talk on speakerphone, but in regular phone I could not hear what the other party was saying and they could not hear me.
- For a while, all audio failed for music, podcasts, etc... sound failed for everything except speakerphone.
Solution: Plug in the headphones. Listen to some music. Then pull out the headphones. This seems to have reset the internal states so that the iPhone audio is working again.