1. Audio cable is not plugged in. Please check whether the audio cable is plugged in. If you plug it in, you still can't play music. Please try replacing the audio cable.
2. The volume switch is not turned on. Please check whether the volume switch is on. If so, the volume is not high. Please check whether the volume of your computer or music player is turned up.
3. No audio device is selected. Please check whether the correct audio device is selected. If the wrong device is selected, you may not be able to play music.
4. The projector audio interface is damaged. Please check whether the audio interface is damaged. If damaged, it may need to be repaired or replaced.
5. Audio format is not supported. Please check whether the projector supports this audio format. If not, convert the audio format.
Summary:
These are the reasons why the projector can't play music. If this happens, we can try to solve the problem from these aspects. Because of many reasons, the solution may not be effective, so it is necessary to adjust the method according to the specific situation or seek professional technical support.