Windows10 deleted files and apps from desktop

Hi

I’m the family CTO/CIO which is frightening in and of itself. 

Last night, Windows 10 shut down our desktop and upon restarting, apps and files are no longer there (it deleted about 550 files).  I’ve googled the issue and I think it has to do with Windows 10 changing our profile —- but I’m not 100% certain .  Chrome, Spotify and other apps that rely on Chrome are gone as are hundreds of personal files ( which I believe are backed up somewhere on OneDrive). The steps I see and try to follow are not applicable because some of the things I’m told to look for do not exist on my desktop. 

Please can someone point me to a comprehensive approach and/or video I can watch to correct this. And, it would be helpful to know why it happened so I can try to avoid the same sitch in the future.