There is a volume control on the youtube video screen, to the right of the progress bar. It might be muted.
Often it’s as simple as the mute is on or someone turned down the volume in one of the menus.
Has anyone got a “Downfall” clip of Hitler ranting about how he has no sound when playing youtube clips?
Are you logged in?
(I’ve always wanted to say that)
*All* the volume controls in your computer universe have to be turned up some...including the little speaker icon down in the lower right. You might have to visit “control panel” and diddle with things.
Is your sound out completely? Or is it only on youtube?
If no sound at all, then it could be your sound-card on your motherboard isn’t working.
Try plugging in headphones and see if your sound works through them.
Does the no-sound issue happen in any browser you use? Sometimes I could not get sound in Firefox but could in IE. Try another browser and see if that works. Could be that you need to update a plug-in or something.
Are you trying to stream something else on the computer while you’re playing YouTube videos? If so, stop what you’re streaming and then re-load the YouTube video and see if the YouTube sound works.
For some odd reason, I can’t get audio from YouTube videos if I’m streaming something else on the computer at the same time.
It usually means that the cat has walked across the keyboard.