If you are getting no sound in Internet Explorer 9 there are a few things that you can try to get the sound back on
The no sound problem is common in Internet Explorer since version 7, so what I am saying here may apply dating back IE 7. The first thing you want to do is go to check other programs on the PC for sound. The next thing to do is to check another web browser like Firefox or Google Chrome for sound. If the other web browser is working than you know the issue is with Internet Explorer 9."No Sound In Internet Explorer 9"