I lost pictures that had not been saved to the sd card, can they be retrieved?

It depends on when they were deleted. Samsung backs up deleted photos to your Samsung Cloud for up to 15 days after deletion. Follow these steps and hopefully you can retrieve your photos from the cloud: Settings, Samsung Cloud, Gallery and Trash. Once in trash, select the photos you want to restore and select restore.

If that doesn’t work for you, try using a photo recovery tool. Stellar Photo Recovery Software is a good choice, google it.

Hope this helps

With the modern technology, in most Android phones, photos does auto backing up of photos once your internet is on. Go to photos you'll find your lost photos

Remove your sd from phone and connect to laptop and install easeus data recovery
you can get any file

Try Hetman Photo Recovery. This is software espesially for recovering pictures from any type of storage. https://hetmanrecovery.com/digital_photo_recovery/hetman_photo_recovery.htm

You can try data recovery tool,
Recover Lost Data Files from Android Phone

the photos, text messages, contacts, memos all can be recovered with it,
Recover Deleted Photos Pictures from Android Phone

Coolmuster Samsung Data Recovery excellent tool used for data recovery. Coolmuster Samsung Data Recovery which is designed for recovering all the deleted as well as lost and formatted messages as well as contacts, photos, videos from Android Devices. How Can Recover Deleted Pictures on Android Phone

You can try GT Recovery to restore deleted pictures! Lost your photos on Android phone & need to recover deleted pictures, try GT Recovery for Android - the World's 1st Data Recovery Software for Android smart phones.
It can directly recover deleted pictures, photos lost due to deleting, restoring factory settings, flashing ROM, rooting, etc., from SD cards inside Android devices. It let you preview the deleted photos before recovery. Watch the video tutorial to learn how to retrieve photos from Android phone easily with simple clicks.
Key features of Data Recovery - GT Recovery for Android:
Preview & selectively retrieve photos and video lost due to any problem
Support all Android phones/tablets, like Samsung, HTC, LG, Motorola...
Only read and recover the data, no personal info leaking, 100% safe
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They can be assuming the card isn't faulty and assuming you haven't been adding and deleting data off of it since loosing the data you want to retrieve

, I would advise using something like this:
(its worked for me i the past)

Data Recovery Wizard Free 8 6