themes-wordpress/button-2/404.php

<?php
/**
 * The template for displaying 404 pages (not found).
 *
 * @package Button 2
 */

get_header(); ?>

	<div id="primary" class="content-area">
		<main id="main" class="site-main" role="main">

		<section class="error-404 not-found">
	<header class="page-header">
		<h1 class="page-title"><?php esc_html_e( 'Oops! That page can&rsquo;t be found.', 'button-2' ); ?></h1>
	</header><!-- .page-header -->

	<div class="page-content">
		<p><?php esc_html_e( 'It looks like nothing was found at this location. Maybe try a search?', 'button-2' ); ?></p>

		<?php get_search_form(); ?>

	</div><!-- .page-content -->
</section><!-- .error-404 -->

		</main><!-- #main -->
	</div><!-- #primary -->
<?php get_sidebar(); ?>
<?php get_footer(); ?>