Recently came across this strangeness. A coworker was trying to view a video posted on YouTube, but no matter what he did, he couldn’t get the sound to un-mute in Chrome. The volume slider would not move, nor would the sound icon respond to mouse clicks.
It took a little research on several forums to find that a recent flash update was the culprit. The solution was to go into Chrome’s settings and delete an hour worth of cookies. Once the cookies were cleared, we regained control of his audio.