Re: Where could the MP3 Ringtones be that I transferred from my PC to my Nokia Lumina 1320?
If you can play on your phone, it isn't protected with digital rights management (DRM), and it's smaller than 30 MB, then you can use it as a ringtone on your phone.
It has to come from the PC, not the phone, not OneDrive, not a zip file. The ringtone folder in phone memory, not one you created on an SD card, not one you created anywhere.
Put the ringtones in the music folder to see if they will play on the phone, do they play on the PC.
You do not have access to the native ringtones on the phone. They are part of the system.
When you select a ringtone for a contact it will be in the custom folder, not listed with the other ringtones.