Problem details (based on the original message we've got):
"Hi! I could really use your help and guidance. I discover a few days ago that my pictures taken with the camera of my phone have disappeared from my gallery. I didn't deleted them (I'm sure because they were important for a research I'm doing), and they were all saved in the internal memory of my S3.
I've looked for them in DCIM directory, also went thru all the folders available on "My Files." I installed a couple of explorers similar to the ones on PCs, see if that helped me but no lock. The weird thing is that the pictures saved on folders with specific names on Camera App, are still there. The ones missing were saved in a Camera folder that the phone produces."
A. Recover missing photos with Android Data Recovery
Android Data Recovery is one of the highly recommended recovery software used in retrieving lost media files (photos or videos) from a Samsung Galaxy device's internal memor card/SD card, including the Galaxy S3.
To recover your missing photos with the Android Data Recovery, you need to download it first (for free at androidrecovery.com). Just select a version you want, either a Windows or Mac version. To ensure everything is safe, be sure to backup your data before using the recovery software to retrieve lost files from your S3.
After you've created a backup, follow these steps:
1. Download and install the program. Choose a version you want to use, then download, install and run it on your computer.
2. Connect your Galaxy S3 to your computer with a USB cable. When both devices are successfully connected, you will be prompted to "Enable USB debugging."
3. Enable USB debugging based on the following conditions:
* If your Galaxy S3 is running Android 2.3 or earlier versions, follow these steps to enable USB debugging on your device:
a. Go to Settings.
b. Click on Applications.
c. Click on Development.
d. Mark or put a check on USB Debugging.
* If your Galaxy S3 is running Android 3.0 to 4.1, follow these steps to enable USB debugging on your device:
a. Go to Settings.
b. Click on Developer options.
c. Mark or put a check on USB debugging.
* If your Galaxy S3 is running Android 4.2 or later versions, follow these steps to enable USB debugging on your device:
a. Go to Settings.
b. Click on About Phone.
c. Tap on Build Number for several times until you are prompted with a message saying, "You are under developer mode."
d. Go back to Settings.
e. Click on Developer options.
f. Put a check mark on USB debugging.
Now that USB Debugging option is already enabled on your device, you may now proceed to the next step.
3. Start analyzing and scan your Galaxy S3
On your computer, you will be prompted with the screen containing the steps to connect your device and initiate scanning. Click on the Start button to begin the process.
4. You will then be asked to choose which type of files you want to scan. Just put a check mark next to Gallery, or check Select all to scan all files on your device. Click on Next to proceed.
5. Select a storage scanning mode (Standard or Advanced). If the initial scanning failed to retrieve the lost files, then try a different scanning mode.
//Standard mode - There are two options you can choose under standard mode scanning.
You can try "Scan for deleted files" just in case the files were accidentally deleted. Click on Next to proceed with this scanning mode. This will take less time because the program will only scan all deleted files on your device.
Otherwise, if you choose to Scan for all files, then the recovery program will scan all the files on your device, thus it will take longer to complete. The good thing though is that it can find or retrieve more complete files.
//Advanced Mode - This will be your next option if standard mode scanning does not retrieve your lost files. This mode however, will take more time to complete.
6. Now, get to your Galaxy S3, and you should see a request prompt on the screen. If prompted, just click on Allow and Start button, one by one. Doing so will let the program scan lost data from your phone.
7. Preview retrievable files in the category of Gallery and Videos from your Samsung Galaxy S3, located at the left side of the screen. Locate the files that you want to retrieve (put a check on the box beneath the photo to retrieve), and then click Recover to save these files on your computer.
To prevent data loss to happen again in the future, please do a frequent backup of your Samsung Galaxy data especially your important data. Just select any of the useful backup programs available for backing up your device, like Android Transfer.
If issue remains after performing the aforesaid procedures, then you may consider doing an internal memory data recovery on your Samsung Galaxy S3. A more detailed guide on Internal Memory Data Recovery is made available at xda developers forum.