my site has been probably hacked. I was running WordPress multisite using not newest version of WP.
Now one of sites have strange home page: http://promusica.edu.pl/ (everywhere, even on http://promusica.edu.pl/wp-admin). I tried to find in files text like "Password:", <pre, and some other to remove this deface. Also I looked in index.php and .htaccess and there is nothing unfamiliar.
What is strange, other site running on the same instance of Wp - http://proregione.org/ is working fine.
Any ideas how can I fix home page of http://promusica.edu.pl/ ?