Did you back them up to any online vault such as Google Drive, DropBox as examples or into any relevant Sd Card @Helen49
Or use Samsung cloud as described here > samsung-cloud-a-better-way-to-upgrade-back-up-and-sync-your-galaxy-device
If not then they will be gone from your Gallery.
There are various software suites usually at a purchase cost that purports to be able to recover deleted items. What level of success these are i cannot confirm or endorse.
Samsung wouldn’t in my opinion be able to assist.
Current Phone ~
Samsung Note 20 Ultra 5G SM-9820 _ Samsung One Ui 2.5/ Android 10. Snapdragon 865+
If you have made a make up file on the computer or Cloud account, it is really simple to access delete photos on your Samsung phone. If not, the only solution is to find a reliable and professional Samsung photo recovery program, so try it.
Yes, it is possible to restore your deleted photos from Samsung galaxy phones. You may try this tutorial that helped me last time: Samsung phone photo recovery solution
It helped me last time. Hope that you can restore your lost photos from your J3 phone.