Error message on any theme

Try switching to the default theme by renaming your current theme’s folder inside wp-content/themes and adding “-old” to the end of the folder name using FTP or whatever file management application your host provides.

on a related note what should the core index.php file for all wordpress installs look like?

I think I may have an error there?

<?php
/**
 * Front to the WordPress application. This file doesn't do anything, but loads
 * wp-blog-header.php which does and tells WordPress to load the theme.
 *
 * @package WordPress
 */

/**
 * Tells WordPress to load the WordPress theme and output it.
 *
 * @var bool
 */
define('WP_USE_THEMES', true);

/** Loads the WordPress Environment and Template */
require('./wp-blog-header.php');

So when I install that I get this error message:

Warning: require(./wp-blog-header.php) [function.require]: failed to open stream: No such file or directory in/websites/123reg/LinuxPackage98/th/ef/oo/thefoolmonty.co.uk/public_html/index.php on line 17

Warning: require(./wp-blog-header.php) [function.require]: failed to open stream: No such file or directory in/websites/123reg/LinuxPackage98/th/ef/oo/thefoolmonty.co.uk/public_html/index.php on line 17

Fatal error: require() [function.require]: Failed opening required ‘./wp-blog-header.php’ (include_path=’.:/usr/local/php52/share/pear:/usr/local/php52/share/php’) in/websites/123reg/LinuxPackage98/th/ef/oo/thefoolmonty.co.uk/public_html/index.php on line 17

Any ideas?

When you install what?

It appears that I had the theme related index.php file in place of the above wordpress file on my pubilc.html file list.

So I got rid of the incorrect one and installed the above one in what I assumed was the correct place.

Try re-uploading all files & folders – except the wp-content folder – from a fresh download of WordPress. Make sure that you delete the old copies of files & folder before uploading the new ones.

If I do that would I likely loose all of my content and plug ins?

No. Your site’s content is in your database & your plugins are inside the wp-content folder.

Okay I did that but I still have the same error showing?

Thank you for all your help. The site is now back up and running.