Reset Microsoft Teams app

To reset the Teams app, perform the following steps

Close the Teams app.
In the Windows menu, find and open Settings.
In settings, click on Apps on the left, then Installed Apps on the right.
Search for Teams and click on the … menu button, then click Advanced options.
Scroll down to the Terminate and Reset sections.
Click on the [Terminate] button.
Click on the [Repair] button.

If that doesn't fix the issue, go back to that section, and click on the [Reset] button.