Given that the photos were on the internal memory, you're most likely going to have to find an "app for that."
An internet search will turn up dozens of these types of apps, some free/share-ware. Please do a search on the apps that you choose to be sure that they have decent reviews. I hesitate to suggest one as they all seem to have their plusses and minuses. Try keywords:
"Android" "Recover Pictures" "Tutorial" "Samsung"
I fear however, that more than likely, if any of your apps or the OS have updated that your images may be corrupted. The only way I know of to prevent that is to switch into airplane mode and from what I understand (mind-you I understand VERY little about the android-os) the newer versions make the recovery much less likely.
Be careful with any method that involves "rooting" a device - something I advise against for the majority of users. Rooting the device can "brick" it if not done properly and/or something important is altered. Also in the US, "rooting" your device might be a violation of your carrier's contract and will most likely void any remaining warranty.