RIP Hope you get your files back
The same thing (almost) happened to me today (05-14-2020). Around 10 AM, I was in the middle of doing a project on my laptop. I had a popup notification that my computer was going to restart to install an update (cumulative update for windows 10 KB4556799). I clicked the 'Not Now' box and continued working. These were supposed to only install after I approved and then, after 8 pm. After around 10 minutes the computer started the update without further notice. It seemed to take forever. Very unusual...
Over an hour later it was finally finished. I resumed my work or tried to! Everything was gone except for very few things. :( The backup was turned off! No file history turned off too!! No restore point because
'a recent update had been performed within the last 10 days'! Most of the day I have been reading and searching for a way to recover all my disappearing files and work. No luck! I am shocked, confused, angry, and bewildered as to what happened & how to find everything.