WordPress forget database settings and launch new installer!

Hello,
I visited a website I made after few months and I noticed that while opening the website it allows me directly to the installation page.

First I made a backup of my whole site, and then I double checked all the settings on the ‘config.php’ file. Everything seems fine even my provider database doesn’t seem corrupted.

What can I do to rescue my website without re-building everything from scratch?

I got all my wp files from the ftp and a backup of the MySQL database.

The website link is this -> http://www.happyhousepisa.com

Thank you for your interest,

Giuseppe