Has this happened to anyone else?

[tentive21]

So I was on my PC this morning and left it for a while, and when I came back, I went on youtube and realized there was no sound, turns out my PC was muted, you know from the mixer. The speaker symbol had a red slash through it. I know a key on my keyboard can do that, but I didn't press it today, I didn't mute it at all, any idea what could've caused this, and should I be worried, can it be a virus? Has anyone else seen this?

 

[broe23]

The Function key got pressed, that controls the mute feature.

 

[tentive21]

Nah I didn't press it and it's on the side of the keyboard I don't use.