Have you checked your photos in iCloud at the web page www.icloud.com in the Photos.app there? You have to open this page on a computer, because the iPhone will display it differently from the desktop version.
Can you see the photos on the iCloud webpage on a computer? All your photos from your camera roll should be there, unless you reset the iPhone before the iCloud upload has been complete or you did not have enough free cloud storage to upload the lot. It may take a while before all photos will come back from iCloud to the iPhone.
If the photos are not in iCloud Photos Library, you cannot recover them from iCloud Photos or the iCloud backup of your iPhone by restoring the iPhone from a backup (Restore your iPhone, iPad, or iPod touch from a backup - Apple Support). The big problem is, that the iCloud backup of an iPhone does not include the Photos Library - all items that are stored in iCloud differently are excluded from the iCloud backup. Do you have perhaps also a backup on computer, made with iTunes? How to back up an iPhone, iPad, iPod Touc… - Apple Community