[ubuntu]Oh! I have changed System settings!

Friends,Many new comers in linux world,may have tried to change system settings or some thing like that,Dont worry! B cool na! Ur solution is here

sudo aptitude --purge reinstall linux-sound-base alsa-base alsa-utils linux-image-`uname -r` linux-ubuntu-modules-`uname -r` libasound2

run this command in terminal!

Thats it!