Right-click in the very small space just above where it says 'Files' and just below the three coloured dots. Select Expand. Then move along the line to the right of the tools (which will now have reappeared) to where the workspaces are selected and reset the display to Default. I'm not sure where your File Edit Multitrack Clip, etc menu selection has gone, that should be available at the top of the screen - presumably this is a Mac thing?
I think you missed the correct place, and were too low, as you clearly hit the panel options. What you are looking for is the short menu with the 'expand' option in it:
If you want to be rather more brutal, try restarting Audition with the Shift key held down. This should restart it in 'vanilla' mode, with everything showing.