Why does OPPOR9s have no sound or display when receiving messages?

You can view Settings-Notifications and Status Bar-Notification Management-Information-Set Breathing Light and Display, and ringtone settings are set in Sound.

How to deal with silent messages received by mobile phones:

1. Check whether the silent mode is turned on on the phone: Settings--Sound--Silent mode--Turn on the complete silent function.

2. Check whether the Do Not Disturb mode is turned on on your phone: Settings - Do Not Disturb Mode.

3. Check whether information notifications are turned off in the mobile phone information settings: Information--Settings--Message Notifications.

4. Check whether a contact is enabled on the phone so that this conversation will not be reminded. Function: Contacts--contact details--no reminder for this conversation.