Hp envy 17 no speaker sound?

I have a HP ENVY 17 and i was trying to put a movie onto my hdtv via HDMI cable, the picture was on the screen but no sound at all so i got my gaming chair's output cable and tried that to no avail but as soon as i pulled the gaming chair cable out the sound on my laptop went off and wouldn't come back on again :( i've tried going on control panel but just got confused and left it now I'm starting to get sick of not having sound, i have tried putting the cable back in the headphone socket but nothing happened, however after i did that i had earphone sound again :) but still its a pain having to get earphones all the time.... any help would be appreciated thanks :)