Dan - Everyone,
Your files are not deleted.
Your files will never be deleted unless you tell Windows you want to delete them.
This Windows 10 Upgrade has been very badly managed, and has cost people a lot of down time and a lot of stress.
Allow me to help:
Please turn on your 'Hidden files' via the File explorer window (any open window in the browser, My Computer, Documents, whatever..).
Once Hidden files is turned on, please go to:
Computer > C:\ > Windows.old > Users
-Please check all the users listed here, then go to:
Computer > C:\ > Windows > Users
-Please check all the users listed here.
Unless you have run Disk Cleanup, other programs, or created roaming profiles your data should be in one of the above locations.
Please understand after the Windows update Microsoft software has put you on a 'Roaming Profile' which is a temporary profile until you sync your settings with a Microsoft Account.
I hope this helps.
-Anthony Harry