1. Check whether the SMS ringtone can be replaced.
2. If the system SMS ringtone can be clicked, please set the information in the SMS-click the menu key-(notify)-select the ringtone to try.
3. If the system's own ringtone cannot be set, please uninstall the recently installed third-party software.
4. Back up the data, and then try to restore the factory settings.
If the problem still exists, it is recommended that you take the purchase invoice, maintenance card and mobile phone to the local Samsung service center for professional engineers to help you test.