I´m sorry about your issue. I hope give you some help and bring back these photos!!
I assume that you import the photos with the app Photos for Mac, correct? In that case, you should open the app and go to the left side of the screen, look for "all photos" option and click there. You should see the photos here or you can choose the option "last importation" when you can see them too.
It´s important be sure that you are in the same photo library that you was the day of the import the photos. You can see your libraries looking for "library" in the spotlight of your mac.
Tell me if the problem has solved!!