If it’s still not working, make sure you’re not casting to a Chromecast, or Google Cast enabled device. Do check this, click on your profile picture in the bottom-right corner and you should see an option for casting.
Ok, so your volume is turned up, and you’re not casting but your audio still isn’t working. What next?
Click on your profile picture again, and select the audio option and make sure that your audio is set to the correct Output.
OK, so you’ve checked all these things and your sound still isn’t working. That’s not a great sign, but all hope is not yet lost. Let’s try a few more things.
First, what exactly isn’t working? Is there no sound coming out of your speakers? Try headphones. Does that work?What about vice versa? Maybe your speakers are working but headphones are not. Do these headphones work in other devices, such as your phone or another computer? Do other headphones work in this Chromebook?
Is it a Bluetooth speaker/headphones not working? That’s probably a Bluetooth problem, not an audio problem. Make sure you check the audio Output sources like I mentioned before. Sometimes Chrome OS doesn’t like to properly switch from internal speakers to Bluetooth and vice versa like it’s supposed to.
Maybe you have a Chrome extension that’s causing your issues. What happens when you log out, and log into Guest Mode? Does sound work there? If so, one of your extensions is interfering.
Do you have some kind of audio equalizer app/extension installed? Check the settings on that and make sure your sound didn’t get muted.