Items such as "save as" missing from menu bar

Can’t access any of the items shown in the menu bar including “help”. Have I done something?

Version of LibO? Operating system?

Try to switch off the option ‘Use OpenGL for all rendering’ under ‘Tools’>‘Options’>‘LibreOffice’>‘View’.
If the menu is misconfigured by accident it should help to reset the user profile.
See https://wiki.documentfoundation.org/UserProfile .

Thanks for the advice. I stumbled on another “solution”. I shut the computer down and when I re-booted the problem was gone.