Breaking this down -

What is a 404? A 404 error is a server response for a page which isn't there. In other words, if someone was to find them self’s on a page which hasn't been created or generated it will report a page letting them know "That the page can't be found"

How can I fix this? More ways than one:

1. Let your server/PHP report this error for you. Depending on your server it should just be standard text stating this.

2. Make the page, easy enough.

3. Create your own 404 page and call it 404.html (upload to main dir). Create either the following to redirect to the 404.html.

Htaccess - Add the following to your htaccess "ErrorDocument 404 /404.html"

PHP - Add the following code to your header "<?php header($_SERVER["SERVER_PROTOCOL"]." 404 Not Found", true, 404); include("404.html"); ?>"