Accessing photos on iPhone iCloud backup
If you have a copy of the backup, there are a couple of ways to get these back.


Free
http://www.itunesextractor.com/extract-photos-from-iphone-backup.html
Paid
https://www.imobie.com/phonerescue/


I would make a backup of your file, then try the free one first and if that doesn't work try the paid version if these photos are important.

Hope one of these will work!