website offline after wrong code :/

Website offline!

http://www.jeegee.eu

I typed a wrong code in the functions.php of the child theme : now website offline and impossible to access to /wp-admin/ .

How can I cancel this last modification ?

I tried to add some text just under the front page slide show. I mixed the method 1 and 2 of this page :

http://presscustomizr.com/snippet/add-content-above-featured-pages/

I am not a pro and just wanted to add some text and a picture just under the slider only on the home page.

I think the code was :

add_filter(‘__before_main_container’ , ‘my_content_before_main_container’ , 0);
function my_content_before_main_container() {
if (! is_home() || !is_front_page() )
return;

function my_content_before_main_container($html) {
$before_main_container = ‘

<img class=” wp-image-347 aligncenter” src=”http://www.jeegee.eu/wp-content/uploads/2015/05/[email protected]&#8221; alt=”Visit us @ Agritechnica 2015 in Hannover, Germany” width=”181″ height=”181″ />

‘; //Put your HTML inside this var
return $before_fp.$html;
}

—-

Help!

My last backup of my webiste is so so old. How can I just cancel the last modification ?

THANKS