Sound not working in my Windows 8 laptop

Hi there,
My problem is related to the sound of my Windows 8 laptop. It is not working at all. I can't hear any sounds except when I connect an external headphones or speakers. The audio works just fine when it is connected. I am guessing that the reason why this issue started is when I plugged my headphones before and maybe I accidentally screwed on the audio port. I checked on all the drivers but it was all working properly. Can anybody help me?
