I noticed that under Setup/Sound and Notifications/Ringtones that there is only one ringtone. The dialog box titled "Chose Path" is directed at /storage/emulated/0/media/audio/notifications and the only file in there is "facebook_ringtone_pop.m4a". (I don't remember pointing my ringtones there so I assume that that happened when I installed Facebook Messenger a few months ago).
The phone ringtone still works on what I set it on last, and the notification ringtone is the Facebook pop. What folder should I point the ringtones at so I have the original default ringtones? I have a Samsung Note 4 running on Verizon.
First find the default ringtones. If you have them backed up, but not on the phone, I created a mp3 folder, in which I have Ringtones (and Notifications and Alarms) subfolders - and it works. (Notice the upper-casing.)