Photos vanished

My photos vanished from a certain period have vanished from my iphone. They aren't in the hidden album or recently deleted and I have icloud photos on from settings. I checked my icloud account and they have vanished from there too. I recently reset my iphone but I had done an icloud backup before that and I don't think that's the problem because those weren't very new pictures and newer pictures are still there. What can I do to get my pictures back and where are they??