What I found very strange is that after uninstall and reinstall the license key was still on the system (which shouldn't have been) and also the buggy switched off toolbars were still gone. In such a situation how can one reactivate the menu?? With Ctrl+F (find) I was able to reactivate one toolbar and then the rest of it with right mouse click.
I had not pressed F9 by accident - as the toolbars were also gone, which does not happen with F9.
This is more a report and not asking for help as I found a solution. Good luck to the team with finding the bug