Hi,
You have probably a .htaccess mod rewrite rule issue, or a malformed permalink setting somewhere as you site ajax handler is not accessible, it redirects to a 404 page: http://www.dezio.it/wp-admin/admin-ajax.php
This URL should return a white page with ‘0’ printed: https://i.imgur.com/GETalIG.png
The misconfiguration also affects your post editor screen, it also redirects to a 404 error page: https://i.imgur.com/mTS4Vsc.png
There are probably other pages that does not work as well.
