Get Welcome to nginx page with my django web project

I am using “one-click” django set up. Website was working fine last week, but I found it cannot redirect to my home page anymore today. It shows: “Welcome to nginx! If you see this page, the nginx web server is successfully installed and working. Further configuration is required.” After searching on old questions, I looked at my “default” file under /etc/nginx/sites-available directory, it already has “root /var/www/html;”. I tried to set listen port to 8080 as well, but it did not work. I do not know what to do now, anyone can help please?