Windows 7: Sound system not working in only windows

I am using Windows 7 professional OS... and i got some problem with my sound system..
But when I rebooted my system with Backtrack OS.. I could listen the startup sound. and nothing other than that. As it is a live OS I am using,i didn't install any media players.. so couldn't check other sounds in Backtrack...



but in windows i couldn't even hear the startup.. I 've tried reinstalling the sound drivers. But it was of no use..

Check in the system device manager, whether you have any yellow marks. If nothing works try to upgrade the BIOS by flashing from USB.Take this as a last option.

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