Odd Windows 10 Reinstallation(?) Situation

So I needed to take the SSD out of my laptop running the most recent build of Windows 10 and edit some data on that SSD on a different computer using an external connector. When I put the SSD back in, I wasn't having any problems with the drive of the OS, but a few days later I turn it on and my desktop is wiped clean and it looks like a completely fresh install of Windows 10. I automatically check to see if my data remains and, oddly enough, it did. My drive was still 4/5 full. The only thing that I can think of that would cause this is when I edited the data of the SSD externally I had to give the other computer permissions to access the data on the drive and maybe my laptop flipped out over it.

Any help would be appreciated. Worst case scenario, I get my data off of the drive and reinstall all my programs.

Is it a fresh install or has a new user account been created? You can check your users by opening Computer Management window (right click on start button) and looking at your Local Users and Groups.