The CarPlay disappeared from my car screen. Help

Unless the "link" between your car and your iPhone was messed up, usually just plugging in your iPhone to your CarPlay compatible car will display CarPlay in your car. However, I suspect each car might be different. For example, in mine, if I switch to satellite radio, then the user interface for satellite radio is displayed regardless if I have my iPhone plugged in or not. If I plug my iPhone in while the satellite radio user interface is displayed, it will not automatically switch to the CarPlay interface for me. I have to manually switch to the CarPlay interface using the controls of my radio.

So if you do not know how to switch to the CarPlay interface if you are viewing another interface (radio, CD, Nav, etc.) then you should contact your car dealer for help.