My iPhone makes no sound whatsoever

The phone displays a volume bar, but it dosen't change to "headset" when I plug something into the jack.

I have tried blowing into the jack, and the docking port but nothing happened.

I can stream sound via AirPlay, and probably bluetooth too - But there is no sound output from the phone when it rings, when I play music with or without headset or during a call.

The microphone does not work either.

Basically, sound does not come in or out of the phone, except for when I use AirPlay.

How do I fix this? Compared to a iphone 4 I have at hand, the dock connector pin seems a bit bent (again, it charges perfectly).

It's a white model, and when I look inside the docking port, there seems to be a bit dirty way inside.