Website suddenly gone crazy and shows code not the site.

The site http://tinyurl.com/gujgg6k has gone bonkers and just displays this code:

SHELL_OK
Array
(
[json_decode] => 1
[curl_init] => 1
[base64_decode] => 1
[gzuncompress] => 1
[phpok] => 1
[has_space] => 1
[index_writable] => 1
[safe_mode_off] => 1
)

When I scroll down I can see the site [albeit a bit messed up] but it's faded out, almost as if it's behind a white background.

I'm also unable to login. If I go to /wp-admin I get:

SHELL_OK
Array
(
[json_decode] => 1
[curl_init] => 1
[base64_decode] => 1
[gzuncompress] => 1
[phpok] => 1
[has_space] => 1
[index_writable] => 1
[safe_mode_off] => 1
)

Warning: Cannot modify header information - headers already sent by (output started at /home/freshl21/public_html/realetc.co.uk/wp-content/mu-plugins/test2ssss.php:35) in /home/freshl21/public_html/realetc.co.uk/wp-includes/pluggable.php on line 1174

I'm not sure what to do here as it was working finer earlier today! Can you help please?