Lost photos in iPhone 6s

I woke up last Wednesday, and all my photos were gone on my iPhone. Only 18 were there from 2018. I spent 5 1/2 hours with Apple support who said they probably are there in iCloud and the only way to access them, was to reset the phone. The phone showed a huge amount , 1GB in back up and they said that was the only way to access them. I tried resetting the phone, it did not work. I cannot find them anywhere. What’s the point of having iCloud back up if you can’t access it?