Have you retrieved your lost photos from Galaxy? If not, you can follow the steps below to get some back. Hope it helps you somewhat.
- Stop using your phone and turn off the WiFi and 3G/4G connection to
avoid automatic updates and data overwriting(I guess you didn't know about it, that's OK, try your luck.)
- Check the available backups. It is easy to retrieve deleted data from Samsung if you have backups. Simple syncing the data with Samsung（Omit the detailed steps）.
- No backups? there is no need to be panic either. Get a reliable Samsung Data Recovery tool to do the job.
- Basically, as long as the deleted data not be overwritten, the android data recovery program can help you get them back.