Please use the below steps to turn your microphone or camera back on.
Navigate to settings
Go to Privacy
Navigate to either "microphone" or "camera".
Switch the slider from off to on
If the above is blocked by admin use the below steps.
Search for "edit group policy"
Then go to Administrative templates.
Select Windows components > App Privacy
Then you want to double click both the below and enable them.
Click on the drop-down next to Default for all apps to change the setting as below: