site down?

Hi
I accessed my dashboard and wanted to see one of my articles and I found myself on the setup WP page. It’s like I have to set up a new MySQL DB.
All my files and articles are still there but not accessible through the website but via dashboard.
I went to my Cpanel and I’ve seen that there is a new WP folder that has been installed in the public folder. I was surprised as I did nothing for that.
I checked the php file wp-config.php and everything is fine there, BUT there is another wp-config-sample.php with no set up for the DB.

I don’t know how to fix this and how this happened.

I’m not a geeky person and my english skills seem poor when I try to speak geeky language. Please help
!