Use Windows Driver Rollback feature or System Restore to when it worked.
I have W7 64 bit Home premium. I upgraded the my reltek audio drivers to latest R2.67 vesion. I can't hear audio from youtube videos. I can play winamp, media player and audio is loud and clear. I can pay videos embed in yahoo sites, i can play videos from cnn, msnbc sites. What is happening here. Can someone help me.