After deleting preferences I note that many of my collections are missing. In particular JFridel PHOTOSAFE COLLECTION, and others.
Am long time user.
Deleting preferences does not cause collections to be deleted from a catalog.
Make sure you are in the same Lightroom in which you were working before getting rid of preferences.
If that does not help, try accessing the most recent backup if you back up your catalogs regularly.
Retrieving data ...