How to use external speakers while headphones plugged in?

I had/have a similar problem. Go to the control panel, then to hardware and sound, then sound. You should see something called manage audio devices. Plug in your headphones and see if they show up. If they don't, then either your divers(these things will tell your computer what kind of hardware it has and how to use it) are missing or the the headphone jack itself has failed. Lets say it is in fact your drivers that are missing, then all you need to do is either use windows update(it will detect many of your missing drivers) or go to the manufacturers website and look for them there(usually they will have a tab somewhere on the home page that will say something about support or downloads). And also try different headphones, those could have messed up as well. Now lets say that you do see the headphones show up as an audio device. Then all you need to do is set them as the default and that should fix your problem. Though I will say that I currently have a problem with switching between the two. Once I start a program such as media player, it will stick with the current default audio device. I hope that helps you. http://en.kioskea.net/forum/affich-55303-no-sound-from-my-laptop-headphone-jack

On mac: open system preferences then click sound, further down the window there should be a selection bar saying sound output simply change that to sound input Sadly i do not know how to disable the headphone jack on windows but i will keep looking Hope this helped