Redmi k30 cell phone keeps ringing. Why can't you hear the sound?

There may be a problem with the speaker, and the MIUI version is too low.

Solution:

In the new version of MIUI, the voice assistant function can set the volume for different applications. If the application is only partially muted, you can adjust the volume in the application, or turn off the "multi-application media sound adjustment" function in phone settings-sound touch-sound assistant. Check whether mute and do not disturb mode are turned on. When the related mode is turned on, icons such as bell and moon will appear on the left side of the signal icon. If there is no wired earphone connected, but the earphone icon is displayed in the notification bar, it may be that the earphone jack is faulty. You can clean the headphone jack.