Your camera roll photos (and videos) would be stored in your iPhone backup, if you have one. If your backup is in iCloud, you would have to restore another iOS device to the entire backup in order to access them. If your backup is on your computer, you can either restore another iOS device to the backup, or use 3rd party software such as iPhone Backup Extractor to extract the photos from the backup.
If your photos are in photo stream, you could recover photos added within the last 30 days by syncing another iOS device or computer with your iCloud account and enabling photo stream. (Photos older than 30 days are removed from photo stream.)