Microsoft released the Windows 10 v1909 and v1903 KB4532693 cumulative update as part of their February Patch Tuesday updates. Reports are starting to come in that after installing the update, some users state that their normal user profile is missing, their desktop files are missing, and their Start Menu is reset to default. A bug in the update is loading up a temporary profile to be used during the update process and failing to restore the user’s profile when done. After some Registry editing and folder renaming, the user was able to recover the profile and get things back to normal.
Source: https://www.bleepingcomputer.com/news/microsoft/windows-10-kb4532693-update-bug-hides-user-data-loads-wrong-profile/