I somehow made it full screen with a click
Go to Solution.
command + Shift + F (on mac), F11 on win.
As ideato suggested, F11 will do the job on Windows.
But that only brings you back from the full screen mode.
If you wish to get back your toolbar and menu bar, left click
There you will find Options.
When you click on options, you will find Menu Bar and Navigation Toolbar.
Simply selecting them will do the job (if they are not already selected).