I was out walking, plugged my Skull Candy headphones into the jack and fired up the native media player. Nothing came out. The counter was moving forward, meaning the music was playing. When I got home, I tested it without the headphones and the music played over the phone's speaker. I then plugged the phones back in and got nothing except the alerts over the phones.
I then rebooted and music playback through the headphones was restored.
Can anyone tell me why this happened?