Hi Prakash and welcome to the forum. Just for future reference..This would have been better posted in the section called 'Support' as you'll get a better response.
Anyhow.. Back to your problem, First of all Prakash can you post some details of what your using( pc spec) and how it came to be that way (how did you lose the audio)
Hey Bios can you move this to the multimedia thread?
now back to the issue..yes any USEFUL information is helpful. what brand of sound card are you running and whatever else you can tell us. If it is a sound blaster you can download "Danial's" drivers. I've herd it has helped a lot of people.
I'm sure Kemical knows where you can get it.