Either by accident or intentionally you clicked on Task View button on Windows 10 and stuck ? Unable to come out of the Task View window?
You could try the following to exit the Task View window.
Right click on any of the Opened tabs and click on Snap Left or Snap Right. Which will take you out of Task View window.
To hide Task View icon from the Task bar, right click on the Task View button and deselect the “Show Task View button”.