tuhina1101 Said:
"Question mark instead of launchpad in dock: One day, randomly, a question mark started showing up instead of what used to be the launchpad on my Mac. I have (as a temporary solution), added the "Applications" folder in the dock, but not been able to bring the launchpad back. How do I bring it back?"
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Go Here: If the Dock on your Mac Contains a Question Mark - Apple Support
A Deleted App:
You've deleted the app from your Mac, but the app resides on the Dock.
Reinstall the macOS:
To reinstall this items, reinstall the MacOS. Nothing would be deleted. It's just that items that have become corrupted or deleted, would be replaced or reinstalled back to where they should be. Go Here: How to reinstall macOS from macOS Recovery - Apple Support
Important:
Create a Time Machine Backup, First:
Prior to the re-installation of your macOS, be certain to backup your Mac using a Time Machine Backup. That way, you can have something to restore your Mac from, should anything go wrong with the reinstall. Use an external hard drive that is at least 1.5 the total storage capacity.