1. Connect your phone to PC in Disk drive mode.
2. Your phone’s SD card is mounted as a drive on your computer.
3. On sd card go to media > audio > notifications and then put the music files in this folder.
4. Disconnect your phone from PC. So, your phone can access SD Card.
5. Go to Settings > Sound > Phone ringtone > (name of the files you copied will show here, select it)
- Mihir Patel