Here is my understanding of the issue here.
You have a folder with picture files in it.
All the pictures in that folder have the hidden attribute so can only be seen by showing hidden files which makes them appear with the shaded icons.
You wish to use those pictures in a windows screensaver picture slideshow but when you select the folder containing the pictures it shows the folder as empty even though you know there are pictures there because you saw them when viewing hidden files.
The reason the screensaver doesnt see the pictures is because they are hidden. Even with selecting to show hidden files, the screensaver will not use a picture with the hidden attribute. you have 2 options that would work to get the pictures to show in the pic screensaver.
1. unhide all the pictures so that the screensaver can access them. you can do this by selecting all the pictures, right-click and select properties, and unchecking the hidden attribute and hitting apply.
2. if you still wish to have the pictures show in the screen saver but remain hidden for some reason, then still unhide all the pictures, direct the screen saver to the folder that contains the pictures, and then hide the FOLDER that contains the pictures making sure to only check "apply changes to this folder only". that way, the pics are still in a hidden folder, but the pics themselves are not hidden and the screensaver will be able to access them.
if these pics are in the main pictures folder for windows, i would suggest putting them in a subfolder and hiding that subfolder instead of hiding the main pictures folder.