Windows 10 File Explorer Search Not Working

As a workaround, use Cortana

As per Microsoft Support, the preferred method of Search in Windows 10 is Cortana, accessed by clicking the box on the bottom left-hand side of the screen where it says 'Type here to search'.

Type the name of a document (or a keyword from it) into the search box on the taskbar. You'll see results for documents across your PC and OneDrive under 'Best match'.

There are many factors that can cause this problem.

You can try the following methods first to see if the problem can be solved.

1.Restart your computer

2.Restart Cortana / Search process

3.Modify Windows Search service

4.Restore indexing services

5.Run the built-in troubleshooter

For detailed information, you can refer to the link.