The server does not recognize "index.php" as a valid directory index file.  You'll want to contact your server admin and have them include "index.php" as one of the directory indexes so that the "index.php" page loads automatically.

 

Currently, the server is simply listing files within a directory.  It should be loading "index.php" as a default.  There are few methods to accomplish this.

 

source: http://websistent.com/change-the-default-directory-index/

 

Method 1: Edit the httpd.conf file
This method is suited for someone who uses a dedicated server/VPS. Open the httpd.conf file using a text editor and search for the following line (be sure the DirectoryIndex includes index.php.

<IfModule dir_module>
DirectoryIndex index.html index.htm index.php
</IfModule>

 

Save the file and restart Apache Server. If it refuses to start then check for syntax errors.

 

Method 2: Create/Edit .htaccess File
This method is for the most of us who host our websites on a shared server. Create a file named .htaccess (the dot at the beginning of the filename is very important) inside the directory that you'd like for it to load index.php instead of listing the directory contents. If it already exists edit it and add the desired filenames. For example:

 

DirectoryIndex index.html index.htm index.php

 

Save the .htaccess file. You can also do this for specific directories by creating .htaccess files inside specific directories and inputting the desired filenames. If you get a “500 Internal server error” check the syntax of the .htaccess file.