Sound problems

Hello,


few days ago i had format my "acer aspire 5920" laptop. then installed "XP sp2" & updated it to "SP3".

after which i can not surf any video/youtube. also i can't use "sound wheel" of my laptop.

i am not able to use "WMP" as it giving error "Windows Media Player cannot play the file because there is a problem with your sound device. There might not be a sound device installed on your computer, it might be in use by another program, or it might not be functioning properly".

Altough i m able to acsess music audio/video from "VLC" media player via both the Laptop speaker & external sound box.

I have tried all possible solution including installing proper "flash player", enabling all reqired setting from both "explorer & sysem " tools & settings.

Please, resolve my problem as i m very confused & frustate.

Thanks.