Hello.
You can check your Gallery app - Menu settings are set to Content to Display - All.
Search with a file explorer app like ES File Explorer (or My Files app comes with a Samsung).
Or search with Windows Explorer on a pc via usb to find the DCIM folder.
Have your settings automatically synced them to Google Photos / Picasa or to your Google + account if you have one.
You can search your Google accounts or Google Drive.