If you can't turn on iCloud Photo synchronization on the phone itself, it is too late to do so now. Those photos and videos are not in iCloud Photos, and are not going to be in iCloud Photos, You cannot recover them that way.
Did you save copies of those photos in some other way? For instance, were you making backups of your iPhone to iCloud, and did those backups include photos? Were you making manual backups to a Mac or PC using iTunes, or the Finder? Did you manually import those photos to a Mac or PC in any of various ways? Did you send any of the photos to friends or family members in e-mails or text messages (leaving open the possibility of getting them back from the recipients)? Etc.?
If not, sorry, but those photos are gone. Backups must be made before catastrophe strikes. Afterwards is too late.