Important options (“Settings”, recent notifications; edit privacy settings, etc.) were at the top of every Facebook page IIRC, toward the right. Now they appear in none of the Facebook pages.
I use a laptop, not a smartphone. I don’t use Facebook facilities much — I think my favorite option is “Log Out.” 
But this morning I am unable to Log Out. Or to do any of the things (such as changing privacy options, etc.) that are done with the menus available at the screen’s upper right. All those menus have disappeared.
I’ve looked for those menu headers all over the Facebook page. They aren’t among the 31 icons stacked vertically at the left of the page. Nor are they to be found among the six or so other places on the page that contain clickable options. Nor do they appear if I click on any of the three places with names like “More Options.” If I click on my own name, I go to a different page with other options and without the long list at the left. But the “important” options (See recent notifications, Edit Privacy; Logout; etc.) are still missing. Changing Newsfeed between List and Grid doesn’t help. There is a More->Manage Sections option, but the Sections I can Manage from that menu do not include Settings, Privacy, Notifications, etc.
I’d log in to a different account and see if it’s also affected. However I don’t know how to do that without first logging out of my own account and I can’t even do that!