Unhook child theme error page 404.php
To create a child theme you need to create a two files style.css and funtions.php first. Just create a interface-pro child folder inside wp-content/themes. Under style.css file add this below code
/*
Theme Name: interface Pro Child Theme
Author: Self-Help WordPress User
Template: interface
*/
@import url("../interface-pro/style.css");
Under funtions.php you need to create your functions first unhook the functions and then only customize the code. Below is the example how to unhook function page 404.php, You do same for other too.
unhook functions
// Unhook default Thematic functions
function unhook_thematic_functions() {
// Don't forget the position number if the original function has one
remove_action( ‘interface_404_content', ‘interface_display_404_page_content', 10 );
}
add_action('init','unhook_thematic_functions'); // removes the header content by using hook interface_header
add_action( ‘interface_404_content', ‘interface_child_display_404_page_content', 10 );
/**
* function to show the footer info, copyright information
*/
function interface_child_display_404_page_content() { ?>
<div id="content">
<header class="entry-header">
<h1 class="entry-title"><?php _e( 'Error 404-Page NOT Found', ‘interface’ ); ?></h1>
</header>
<div class="entry-content clearfix" >
<p>Thank you</p>
</div><!-- .entry-content -->
</div><!-- #content -->
<?php
}
If you are still unable to fix it then you need to hire a developer to fix it.
Thank you!