Start with this...
On your Mac, choose Apple menu > Shut Down.
Wait for your Mac to shut down completely. A Mac is completely shut down when the screen is black and any lights (including in the Touch Bar) are off.
Press and hold the power button on your Mac until “Loading startup options” appears.
Select a volume.
Press and hold the Shift key, then click Continue in Safe Mode.
The computer restarts automatically. When the login window appears, you should see “Safe Boot” in the menu bar.
Restart normally.
Open Terminal and run each of these one at a time
/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -r -domain local -domain system -domain user
sudo /System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -kill -seed -lint -r -f -v -dump -domain local -domain system -domain user -domain network
killall Dock
sudo mdutil -E /
sudo mdutil -i on /
Rebuilding a drive index can take a long time, so be prepared to wait whether you do it through the System Preference panel or the command line.