Have you been using Photos or Image Capture to import the photos?
If you have been using Photos, check, if you have opened the correct Photos Library on your Mac.
- Hold down the options key ⌥ while launching Photos.
- When the Library Chooser dialog appears, select each library in turn, if there are several libraries to choose from.
Does one of the libraries hold your Photos?
If not - what happened, after you imported the photos?
Did Photos give you a message that the photos have been imported successfully, or did Photos quit unexpectedly?
Do not restart the Mac, until you found the photos. They may still be in some caches, that would be cleared when you restart the Mac.