Once in download mode make sure you have the samsung drivers for pc.
Connect your phone to the pc. Once there see if you can see its contents via start icon --> computer --> will be listed under external storage devices. Double left click it to open its folder structure.
Next go to Recuva - Download Download the Recuva program and install it "without the yahoo toolbar".
Once running recuva point to the phones drive or folder you wish to scan and scan it for deleted files, may or may not find, depends on how much the factory restore deleted and repartitioned.