Check your ZenFone's earphone jack and earphone ：
Check your earphone is well plugged into your ZenFone's earphone jack. If not, you may not hear any sound from your earphone.
Check sound setting when your earphone is plugged into the ZenFone：
1. Plug you earphone to the ZenFone and tap Settings > Sound.
2. If your Media volume is mute, you will not hear any Media sound from your earphone.
3. Turn on the Media volume.
Power off and Power on your ZenFone：
Power off and Power on your Zenfone and check whether you hear sounds from your earphone.
Plug your earphone to other audio devices：
If you still can't hear any sound even connect your earphone to other audio devices, your earphone may be broken, please try other earphones and check again.
Enter Safe Mode：
If you can hear sounds while entering the Safe Mode, 3rd party app may be the root cause. Exit the Safe mode and check again.
How to Enter and Exit Safe Mode on Android phone ?