Sound heard through headphones, but not with internal speakers

Question

Recently, my computer stopped producing sound from the speakers. However, I plug in headphones and everything can be heard. I've already checked Sound in System Preferences. Nothing is muted and all sliders are in the correct position. In the Output Pane, my only option for the output source is headphones, no internal speakers. What happened? What should I do?

Answer 1

I recently got the same problem. Its not that bad but confused me at first. If that is the worst problem you get with your computer consider yourself lucky. You could bring it by an apple store genius and see what they say but its most likely a switch problem like tteuer said. If my memory serves me right that switch is connected to the logic board, if you have it still under warranty, great, if not, you might as well get another laptop if it really bothers you.
Tip: I have made it work by either slowly removing the headphone from the jack or rotating it. If that did not work the first time I repeated it.