Is it possible to retrieve photos from a disabled iphone that has not been backed up?

Unfortunately, no. If you have to reset the device because you forgot your passcode, or if something else necessitates reinstalling the OS, there is no way to retrieve items on the device. It's good practice to backup frequently and/or to use the tools provided by Apple (iCloud backup, iCloud synching) to reduce loss in the future.

If you have been using iCloud Photo to sync your photos to iCloud you are in luck:

If you're missing photos or videos in the Photos app - Apple Support