Cat stepped on my laptop and now there's no sound :(/

Greetings,

I was watching a movie yesterday and intended to pick up where I left off today, only to find myself met with total silence... there's no sound at all. My cat had a few minutes of unsupervised access to my laptop earlier; she has a rather unfortunate habit of wandering across the keyboard and lounging on the keys. I suspect she might have toggled some setting, though I've scanned the interface and can't find a single icon indicating that anything has been muted or disabled...
To complicate matters, I attempted to install a new version of YouTube yesterday, which ended up freezing mid-process. It sat there indefinitely, stuck on an "initializing" screen that refused to respond to any attempt to close it. I can't help but wonder if, in my haste to update YouTube, I inadvertently invited a virus onto my system?
My machine is a Lenovo, only a few months old, running Windows 8.
I am at my wit's end here, friends. Please, I'm desperate...😵

Do you see any yellow warning icons or question marks showing up in your Device Manager?
Download, install, and run the updates, then maybe give the laptop a scan using Norton AntiMalware just to be safe.