Electricity

Why does my car not have any electricity? When I drive somewhere and park and turn the ignition off, all the electricity in the car shuts off and won’t come back on. Slamming the door hard would make the electricity come back and the screen on the dashboard turn back on. Normally, the media system/radio would stay on until I open my driver side door but it all just shuts off. The lock and unlock button on the doors and the keys won’t work. I can’t turn the car back on at all. The battery is not corroded or have any loose connections, the ground wires are all working. Why is my car losing all electrical power.