In case you have the following problem scenario on your iPhone, here’s a quick tip :

• sound via headphones, no sound via the speakers
• your phone rings ok, but
• everything else you can’t hear except via the headphones

Then you need to plug in-and-out your headphones. Go on, have some iPhone intercourse !

Do that about 3 to 6 times and normally it’ll start working again. I noticed that my audio output started working again when suddenly my ipod screen came up.