I’m editing 404.php file and trying to display the same header as it is displayed on the home page. Normally, I can choose from a list of headers from my theme, when I create or edit a page. 
The problem is that I have to edit 404.php to customize the "not found 404" page. I have only one file header.php, so get_header() function from 404.php is not rendering the header I want.
What I have to do?