Youtube has no sound

I'm not sure if it's a problem with my computer or youtube itself but there is no sound on every video on youtube. It's all got this x problem. If it's an April Fools thing, it's a day late but if not what is wrong with youtube and how do I fix it?

 

It seems to be working fine for me.Check your mute buttonsand if its not that try restarting your computer.

 

Are other sounds working?

 

I've already attempted restarting, it is only youtube that does this. It's not my computer because I was watching one piece in another tab at the time and it has the x on the volume button of youtube videos as if it's removed the sound like it would do for copyright infringement, except instead of my videos, it's every video on youtube.

EDIT: It also has nothing to with my accounts or browsers since they all have the same problem logged in or not. I've also tried reinstalling flash player.

 

That's funny, because I have the same problem, but my computer's from 2002. It work's fine on my mom's pc.

 

Try clicking on the x.

 

I already have. It's exactly as if they've removed the sound.

EDIT: I just restarted my computer a couple times. It's working again now. It's no longer greyed out, I can hear it and I can use the volume button again. Thanks for helping guys.