If your phone had automatically backup for example once a day then when you start setting up your phone it will ask if you want to restore data and you select the one that was the newest
Make sure backup is switched on in your settings there is Samsung and Google if you switch them on hopefully your phone did a backup in one of your accounts. If it has you can click restore backup
Also if you use cloud storage such as one drive, your photos may be backed up there in your pictures folder in a folder called Samsung gallery etc hope this helps