Ok, this is an easy one if you stop to think....
so you insert a "plug" into the "jack" and it doesn't divert the sound? You have something physically stopping the connections from being made, or the hardware is bad. One or the other. Turn off your laptop/pc and get some compressed air and clean out the jack....do not blow into it with your mouth you will cause a greater problem.
Do the airphones work in other devices? Try cleaning that plug also.
Try it....I swear I am not in the compressed air biz!