@
bigguwesty,
If its 100% SD card storage remove the card or change your camera settings 2 store on your phone memory, if its actually saving 2 your phone, limit what you download as in apps and change your camera settings to save 2 a memory card.
Every time you save something 2 where ever your lost photo's are you risk the change of over writing them.
Recovering photo's from a memory card I believe is easier then trying 2 recover from phone memory. Also if you try recovering from your pc with phone connected I believe you need 2 have your phone rooted.
As s2 what program is best..... one that actually works and good luck with that, I used an app on my Samsung S5 called DiskDigger, the basic scan worked well but for the full scan the phone needs 2 be rooted which unfortunately I have not achieved on my Samsung S5 although I could do it on my Samsung S4.
The newer the phone the harder it will be