How to restart the Dock without using the command line?
You can force-quit background processes using the Activity Monitor utility. Just find the Dock process (either sort the process list by name, or use the search field in the upper right), select it, then click the Quit button (the icon is an "X" in an octagon) in the upper left of the Activity Monitor window. It'll ask if you want to do a normal Quit or Force Quit.