Seems my host changed something and now my site report an Internal Server Error. I'm not an expert with htaccess file so I don't know what to do to solve the problem. Can you help me please?

The code is the one that October set up during installation, and I can't found a single error in the log

Check the web server error logs for the precise reason.

I tried for 3 days to check the error logs, the server don't generate it. My host keep to say they don't changed anything and that the error is generated before the php level, so the error log won't be generated. If I rename the htacces file the homepage is shown but obviously without any style, script and whit all link broken. How can I do?

Some hosts don't like it if the .htaccess file has permission 777. If this is the case, switch to 755 instead.