No Sound When Headphones Unplugged

I'm running Windows Vista Basic on an HP Compaq laptop. When I unplug my headphones, I can't get audio back in my internal speakers. The sound returns when I restart my computer, but it should automatically switch back after unplugging the headphones. How can I make sure it does that?

check your sound drives.. right click on my computer "properties" then go to device manager.. check the version of the sound card. You might need to upgrade it, either right click and update driver or download the later version for it..
Cheers