I messed up my functions.php and now my site is offline

[mamaganda]

I tried to add some code to the functions php file in the WP editor and now my website returns this message:

Fatal error: Cannot redeclare custom_comment_form_args() (previously declared in /homepages/26/d321801647/htdocs/wp-content/themes/child2011/functions.php:21) in /homepages/26/d321801647/htdocs/wp-content/themes/child2011/functions.php on line 29

here is my functions php code:

<?php
function diw_post_thumbnail_feeds($content) {
global $post;
if(has_post_thumbnail($post->ID)) {
$content = '<div>' . get_the_post_thumbnail($post->ID) . '</div>' . $content;
}
return $content;
}

add_filter('the_excerpt_rss', 'diw_post_thumbnail_feeds');
add_filter('the_content_feed', 'diw_post_thumbnail_feeds');
/** Start the engine **/
require_once(TEMPLATEPATH.'/lib/init.php');

/** Add support for custom background **/
if (function_exists('add_custom_background')) {
add_custom_background();
}

Any help would be greatly appreciated!

Website address - www.wokintime.com