https://www.bleepingcomputer.com/news/microsoft/windows-10-search-is-broken-and-shows-blank-results-how-to-fix/

A bug in the Windows 10 Search is causing blank results to be shown in both the Start Menu and in File Explorer.  This is making it impossible to search for and launch an application from the Start Menu.

Starting today, Windows 10 users all over the world have discovered that when they attempt to use Windows Search from the Start Menu to search for a file or application, the results just come up blank.