How do I retrieve deleted accidental photos?

UFlysoft Photo Recovery for Windows is an advanced utility that recovers lost images, audios, video clips, and pictures from almost all digital cameras, memory cards, hard drives, memory sticks, USB flash drives, and various others. The easy-to-use Photo Recovery utility is available for both Windows (Windows 7, Vista, XP, 2003, 2000, and 2000) and Mac (Mac OS X 10.6 (Snow Leopard), 10.5 (Leopard), 10.4 (Tiger), and 10.3.9 (Panther)Use the Data Recovery for Mac to acheive Photo recovery on Mac) operating systems.

First of all, do not save any new file to camera's memory card.

Take out memory card, and connect it to computer using a card reader. You should see memory card shown as a drive letter (like H:) in Windows Explorer.
Download this camera recovery software named Asoftech photo recovery
http://www.asoftech.com/apr/
Install and open the photo recovery software, select the memory card, and click 'Start' button.

Check out Leawo Photo Recovery Mac, it could recover deleted photos directly from the internal memory of your phone. Should be able to help you get your deleted photos back to your Samsung. Recover Digital Photo Music and Video on Mac OS

When files have been "deleted" from a storage medium, typically, the contents of deleted files are not removed immediately from the drive; instead, references to them in the directory structure are removed, and the space they occupy is made available for later overwriting. Therefore, you can recover the deleted photos with photo recovery program. I recommend Card Data Recovery, easy to use with good function. It has two versions, one for Windows users, one for Mac users. You can download it from the following link:
Card Data Recovery for Windows
Card Data Recovery for Mac

Once you have reformated the SD card that is it!