Accidentally entered the login window while working; is there another way to return to the regular desktop without typing in the password? In other words, how do you exit the login window using shortcut keys or without inputting a password, or is avoiding this step not possible?
If you've accidentally switched to a different user, press ESC or click on Cancel to return to your desktop.

If instead you've landed in the login window, you need to select a user and type the password.