The flash file system of memory cards, although related to removable one, provides better support when you use recovery software, meaning that when you try to recover an image from a memory card the results are in most of the cases, very accurate. For better results, you should connect the card to a card reader attached to the PC into a USB 2.0 port for fast results and better scanning speed and then use the (Eg: Recuva) software to search for deleted images. First time you will open the application, a wizard will ask you what files you want to recover and from what location. For better results, when choosing the scanning mode, check the Deep Scan feature because with it the accuracy of finding deleted files greatly increases. Once files were found, save them to a different location, not in the original one. I have attached an image with the wizard's options.