Visual Editor Tab Disappeared completely

I’m using 2.9.2 (not an option in the drop down above)
Added a post last night – everything was fine and always has been.

Tried to add one today and the Visual Editor tab has disappeared in both create post and create page.

I have done a couple of automatic upgrades – cleared firefox cache – logged out logged back in – checked the thing wasn’t disabled in my user settings… I now have no idea what to do. I have seen this has happened before with 2.8.0 but as above all those fixes made no difference.

Can anybody help please?