How This Tip Works
If you have made a total mess of your Toolbar like
me, there's no button for returning the icons to the default set, but
getting them back there is pretty easy. First, Shift-click on the
white pill-shaped button at the top right of your window's title bar
to bring up the Customize Toolbar dialog. In the bottom left of the
Customize Toolbar dialog, you'll see a set called "the default set."
Drag it up top and it will replace the current icons in your Toolbar.