iPhone Audio Fix

Problem: My iPhone was not working in a lot of ways, all related to sound from the speakers or audio into the microphone. In general, audio was not working on my iPhone. The problem showed itself in various forms:

• 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.