Hello Ranvirk,
I understand that you are getting sound from your speakers and the headphones at the same time.
Do a hard reset.
Turn the computer off.
Remove the power cable and the battery.
Hold down the power button for 15 sec while booth power sources are removed.
This should reset the hardware in the computer.
As you turn it back on tap the F10 key. This will load BIOS setup utility.
Press F9 to load defaults.
Press F10 to save and exit.
When the computer boots back up, check to see if everything is working.
If the problem is still happening, go to device manager and uninstall the IDT audio.
Restart the computer.
This will uninstall and reinstall the driver for the audio.
Here is a link to get to device manager.
Let me know how everything goes.