sandbox-kinderlandwien/sandbox/404.php

<?php get_header() ?>

  <article id="content" class="<?php post_class(array('wrapper', 'container', 'clearfix', 'not-found', 'error404')) ?>">
    <div class="inner">
			<h2 class="title"><?php __( 'Not Found', 'sandbox' ) ?></h2>
			<div class="content">
				<p><?php printf(__( 'Apologies, but we were unable to find what you were looking for. Perhaps  searching will help.', 'sandbox' )); ?></p>
			</div>
			<form id="searchform-404" class="blog-search" method="get" action="<?php echo esc_url( home_url() ) ?>">
				<div>
					<input id="s-404" name="s" class="text" type="text" value="<?php the_search_query() ?>" size="40" />
					<input class="button" type="submit" value="<?php printf(__( 'Find', 'sandbox' )); ?>" />
				</div>
			</form>
		</div>
	</article><!-- .post -->

<?php get_footer() ?>