Do you know why I can't access my php file on my browser but can access the folders?

I have a php project and I can't acess my file when I go in my browser: http://localhost/www/main/index.php.

However, when I go to http://localhost, it displays all my folders of my project.

For information, I'm using LAMP.

The error is just that it can't find the url http://localhost/www/main/index.php

Here is the folder structure of my app :

Could you help me please ?