Well, if they aren't showing on the phone, you might want to try and restart the phone and see if they show then. If not, try connecting the phone to a computer via USB cord and see if you can see in that folder (not using Samsung software to access it, but just Windows and open it as a folder).
If you still cannot find them, they may have been deleted when you deleted others. It happens. There is no guarantee you can get them back, however you can try the following...
There are a few apps/programs out there that 'may' be able to help you recover the data.
A few of the programs you could try would be... DiskDigger, MobiSaver, Android-Recovery and Tenorshare. They are all data recovery apps/programs. There are many others out there...