It is trying to load the image from
http://www.lnx.lorenzobigatti.it/wp-content/uploads/2018/04/tumblr_nxfq7srFDQ1ukmcm5o1_1280-1024x1024.jpg
instead of from http://www.lorenzobigatti.it/wp-content/uploads/2018/04/tumblr_nxfq7srFDQ1ukmcm5o1_1280-1024x1024.jpg
Maybe you moved your website and forgot to adapt the datbase?
Can you just reinstert the thumbnail?
Also I cannot click the menu point because of the same reason.
Please follow this: http://laytheme.com/documentation.html#moving-website