Redirecting WordPress to the homepage. Full article at: http://imelgrat.me/wordpress/dead-links-redirect-avoid-seo-impact/

redirect.php

<?php
	// If you want to redirect the browser every time a page can’t be found while avoiding SEO impact, you can open your 404.php file
	// in your theme’s folder. If it doesn’t exist, then create a blank .php file. Paste the following code in there:
	header("HTTP/1.1 301 Moved Permanently");
	header("Location: " . get_bloginfo('url'));
	exit();
?>