In Windows 8.1
Go to Control Panel
click "hardware and sound"
click sound playback
you get an automatic fix
then adjust sound up loud.
Worked for me!
Possible with Adobe Flash Upgrade.
Any YouTube video, bottom left, 3rd icon in.
Sound Icon - If it has an x to the right, hover and it says unmute.
Click the Sound Icon to unmute.
this worked for me. I had no volume control or sound on youtube.
go to internet explorer options:
Tools / Internet Options
click on the Advanced TAB
Scroll down to - Multi-media
Tick the box:
'Play sounds in webpages'
close IE and re-open
Simply go to your browsing history and clear it to before the time you noticed the no sound event.