If Youtube is still using Flash Player, you'll want to update your version of Flash for your browser (Chrome updates automatically when the most current version of Chrome is installed), then make sure the Flash volume is enabled and turned up. You can usually do this by hovering your mouse over the Flash speaker icon and moving the slider up or down.
The most current version of Flash is 30.0.0.113 but since you didn't tell us your operating system or the browser you're using, I can't give you links to the Flash downloads. So I'll simply say, get the newest version.
Hope this helps
Griif
I can play music from Spotify and other sources(music folder on my computer) but when I go to YouTube I get no audio. Also I get no audio from news sources.

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