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)

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AMD X2 6400+ 3.2GHz BLACK EDITION::SCYTHE SAMURAI COOLER::GA-M51 M/B::3GB DDR2 6400RAM::GEFORCE 8800GTS320/625/900MHz DRIVER '174.74' BETA::160 RAID 0 SATA2::SOUND BLASTER AUDIGY/'DANIELS' DRIVERS::LITE-ON DVD RW/PIONEER DVD::HIPER 530W MODULAR::THERMALTAKE ARMOUR Jr CASE::RAZER COPPERHEAD MOUSE::VISTA HOME PREMIUM SP1