No sound on Laptop speaker

I had similar problem on my Dell Latitude. After unplugging external headphone, I lost sound on my laptop speaker.
The problem was that the switch, where you plug in external device, did not trip back. When haedphone plugged in it worked fine.
So, I plugged in my headphone pins in halfway and gently wiggled it and bingo, my laptop speaker started working again.

In short, if your external device works when plugged in but when the external device is plugged out and laptop speakers does not work, then the problem most probably is the switch within the plug in device.

Hope this will help.

Andy