i encountered the same problem yesterday and then i solved it. Follow the steps. I hope it works for u too..
CONTROL PANEL - HARDWARES AND SOUND - CLICK SOUND - DOUBLE CLICK HEADPHONES OPTION - CLICK LEVELS - UNTICK THE MUTE OPTION AND INCREASE THE VOLUME - CLICK OK
Your problem is solved .
play an audio to check.
if not working still follow the same steps as above instead of the LEVEL option CLICK GENERAL - CLICK PROPERTIES - CLICK CHANGE SETTINGS - CLICK DRIVER - CLICK UPDATE DRIVER - SEARCH AUTOMATICALLY FOR DRIVER ...
INSTALL the driver and play an audio to check.
HOPE THIS HELPS YOU.
if problem not solved still then there is surely some hardware problem with your port. Get it checked asap. THANKYOU