If a factory reset doesn't bring it back, ask Samsung (here it is 1800SAMSUNG) because they modified Android to the point I can't be sure of what they did.
I have recently lost my ability to grant permissions for apps to access my Note 4's system settings.
This is done in the Accessibility folder of the phone which also is the place to make adjustments to asssist people with visual, audio and physical impairments.
I looked at the folder that should contain my accessibility settings and it is empty on both the internal sd and external sd.
Is it possible to download new stock settings?