My mother purchased an All-in-One last year. She has forgotten about all she has known about computers, so I can't explain what happened to the computer, however...
Two days ago, it was fine. Mom went to get on it yesterday, and the only icon showing is the Recycle Bin. I clicked on the Start Icon in the corner, and nothing happened. I opened the Recycle bin, and got the message that the files were corrupt. In the bottom right, her hidden icons are Malwarebytes, and Webtools (Best Buy Geek Squad)
Nothing will open or work. I do not know how to restore anything, and no disks came with the system. I typed in the SID here, but it can't be found.
Assuming that you have Windows 10, click the "Start" button (bottom-left of the screen).
Click the "gear" to open "Settings".
The icons should appear in alphabetical order.
Click to open the "last" one.
You should have a "system restore" option, because Windows makes occasional "check-points" of your critical system files, so that you can select one of those check-points, and "time-warp" your computer backwards.
Select a date-and-time for which your computer was working.
That's just it. No box opens up when I click on the start button. I suspect that GeekSquad deleted everything. (I can't prove it, but they tried to charge her $700 to 'fix' her computer, and I had disputed the charge, and won. Her computer stopped working after that.