Can not access my blog – blocked

Hi, since a week I can not access my wordpress account, I can not do anything, when you try to go on the blog this message appears “Warning: require_once(/htdocs/public/www/wp-content/themes/madison/framework/Theme.php): failed to open stream: No such file or directory in /htdocs/public/www/wp-content/themes/madison/functions.php on line 20 Fatal error: require_once(): Failed opening required ‘/htdocs/public/www/wp-content/themes/madison/framework/Theme.php’ (include_path=’.:/usr/share/php:/usr/share/pear’) in /htdocs/public/www/wp-content/themes/madison/functions.php on line 20”

A friend of mine tried to change the layout and since then everything blocked. Can you please help me to unblock it asap.

Thank you very much in advance,

Audrey