A new problem I ran into lately involved the WordPress post “Visual Editor” tab
As I went in to type my posts, the secondary controls row would hide (the one with bold, italic, paragraphs..etc)
My first thought was a conflicting plugin, so I deactivated everything to check it
Still no solution……
Maybe I CHECKED it in my user profile?
USERS—>YOUR PROFILE – then look for “Disable the visual editor when writing”
Nope, all was good there as well (it should be unchecked)
After countless searches and dead ends, I defaulted to the most basic idea
A re-install of WordPress
Though to simplify that I actually didn’t have to reinstall everything.
I found that by deleting the folder “Wp-Includes“, and then copying it back over from a clean version of WordPress (download to desktop), it was working again
So if this happens to you, then consider overwriting your “WP-Includes” folder

OMG…Thank you so, so much for posting the answer to my problem with the visual editor! I was going crazy trying to figure this out? The solution was:
USERS—>YOUR PROFILE – then look for “Disable the visual editor when writing”
(it should be unchecked) Problem solved!
sure thing!