2010 Mac mini, music only play in lock screen..

[UnityMixer]

hi.

2010 MacMini only play music through head phone jack wen is in '' Put display in sleep'' hot corner action..

yes i know this is wird.

I've drop the keyboard and probably press a shortcut that resulting in THIS nightmare ..
* And i have sound when the hdmi is unplug.
thanks for any help

 

[arw]

Sounds like the default sound output is set to HDMI instead of the headphone jack.
Take a look here:
Click the Apple icon on the top left in the menu bar > System Settings > Sound > Output > Headphones (or similar).

I'm not sure for (High) Sierra but on newer systems you can click or press "alt" and click the little speaker icon in the menu bar and quickly change the sound output.