Graphics card disabled on-board audio, BIOS settings wont help


Oct 7, 2012
I used to use on-board graphics and audio in my PC and everything was working fine.Recently i installed a Nvidia 9400GT on the PC and audio is not working since then.The working audio device is shown as "Digital Audio(S/PDIF)".
now i know the operating system is trying to route the audio through the Graphics card ''TV out'' and i googled around and came to know that all i have to do is to enable the onboard audio from bios and everything should be fine.

in my case, the audio is already enabled in the bios and speakers are listed under (control panel/hardware & sound/sound) along with headphone and digital audio of the GPU, but headphone and speakers are marked as unplugged which they are not.I tried reinstalling the audio driver but didnt work

can anybody tell me what can i do to solve the issue?