The macOS Spotlight service might loose its touch. E.g. when some applications or documents won't show up when you <CMD><SPACE> them. Reason could be that the service or its database got corrupt for some reason.
The following 4 commands will reset the Spotlight service and database. So after you issue those commands the PC/laptop will be re-indexed (which could take a while).
sudo mdutil -a -i off sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist sudo mdutil -a -i on
Now, wait a bit, and everything should be back to normal.