I don't have as many images here because my Chromebook is already setup and I don't want to mess with it
I have had my chromebook for nearly 2 years now.
It updates pretty much every week - BUT randomly the sound stops working.
If this happens to you DON'T PANIC
Note press the button right of your screen to get a quick settings area
Fixing your sound
Mute your sound
If you have a button on your keyboard this is easiest
Shut Down
Use the shutdown button bypressing the bottom right of the screen and the power icon
Turn your chromebook back on and turn the sound up
Check the sound (youtube is normally quickest)
If it hasn't worked- go back to step 1 and try again.