If I've understod things correctly the pathfinder is the thing where everything is listed. So it's a bit surprising that it doesn't seem to be a button or menu option easily available for opening the pathfinder. Or is there?
no problem at all.
Just go to the View tab look to the very left side and find the "Pathfinder" icon.
Scroll to the pathfinder and click it, to change back to st it ON
Pathfiner should be visible again!
besides the tab bar YOu also can look at any other form to find and click the black arrow downside
This also gives You the capability to change, to turn on/Off the different forms of SE