There are many places to check when having problems when the video or sound is not working correctly in Google Meet.
The Chromebook settings:
Click down at the bottom right corner near the time and a little window will pop up
You will see a speaker on the left with a volume bar in the middle and an icon on the right. The icon on the right might show as an arrow or as headphones
Click the icon (arrow or headphones) that shows on the right
Under Input, make sure the Microphone (internal) choice is checked
To adjust the volume, move the dot (on the bar next to the microphone icon) to the left or the right
Google Meet Camera and Microphone Settings:
Click on the video camera icon on the right hand side of the address bar (Way at the end of the address bar after meet.google.com/...)
Make sure Continue allowing https://meet.google.com to access your camera and microphone is checked
Make sure the Microphone: field shows the correct microphone, usually Microphone - Internal Mic if no other microphone is connected
Make sure the Camera: field shows the correct camera, usually Front Camera if no other camera is connected
If either of these fields are incorrect:
Click Manage
Scroll down to Permissions
Click Camera or Microphone (depending on which one is incorrect)
Make sure the correct camera or microphone is selected
Make sure Ask before accessing (recommended) is checked. (If it says Blocked, the camera or microphone will not work)
Close out of this tab
IMPORTANT: Open a new tab and try accessing Google Meet again
Google Meet Connection Settings:
Click the lock icon in the address bar to the left of meet.google.com/...
Make sure Camera is set to Ask or Allow (If it's set to Block, the camera will not work)
Make sure Microphone is set to Ask or Allow (If it's set to Block, the microphone will not work)
Make sure Sound is set to Allow (If it's set to Mute, the sound will not work)
Google Meet Settings:
Click on the 3 white dots at the bottom right corner (in the white bar) of the Google Meet screen
Click Settings
Click Audio or Video, depending on which you'd like to check
Audio - Microphone:
Make sure the correct microphone is selected (Default - Internal Mic) if no other microphone is connected
To test the microphone, make sure the 3 white dots to the right of the microphone icon move when you make noise
Audio - Speakers:
Make sure the correct speakers are selected (Default - Speaker) if no other speakers are connected
To test the speakers, click the speaker icon and make sure you can hear a sound (usually a phone ringing). If you don't hear the sound, be sure to turn the volume up on the Chromebook
Video - Camera:
Make sure the correct camera is selected (Front Camera) if no other camera is connected
To test the camera, look at the video to the right of the camera
Change the Send and Receive resolution to see if the changes make a difference