Check the trash folder of the gallery app. Also check Google photos as they should be backed up there, and check it's trash folder also.~ Unfortunately if they weren't backed up to Google photos or some other method and photos are not found in the trash folders then they are gone for good.
How did the photos get removed? Did you delete them? If you did, they should show in the trash for 30 days. They should be backing up to Google unless you specifically turned that off or your free cloud storage is full. If you decided to clean out the Google backup and deleted your photos from Google, it would also have deleted them from your phone. These will also be in the trash and you can restore them. Once restored from trash they will be restored to a folder in my files called DCIM restored (it may create an album in gallery by the same name. If not, just move the folder into the albums they belong). If they are still in Google photos because they were only deleted from the gallery, you can just download the photos back to your phone.
