The Windows 10 KB4532693 update appears to be deleting users’ files. Users report that their desktop and Start Menu was reset to default settings and that they could no longer find files stored in their user profile. A bug prevented the update from restoring the normal user profile when done. To get this update installed without losing data, one user had to perform a crazy procedure of backing up their profile before performing the update and then restoring it after so that they had their files. If there are no backed-up folders in the C:Users folder, then your profile has been deleted along with all of the data within it.
Source: https://www.bleepingcomputer.com/news/microsoft/windows-10-kb4532693-update-bug-reportedly-deletes-user-files/