Oppor5 sets the bell but there is no sound.

Maybe it's because you turned off the volume of the ringtone. The ringtone, alarm clock and music volume in Android phones are all controlled separately. You go to the main menu → Settings → Sound → Volume → Find the icon with a small speaker and turn it to the maximum, that is, pull the volume bar to the far right to try.

Besides,

If there is no sound after setting, it is that the speaker of your mobile phone is out of order. It is recommended to send it for repair ~