Sometimes, after some changes to the configuration.php file in Joomla, you might find that your website is suddenly trying to redirect to the installation directory. However the page gives a 404 error because the page you are directed to is not found. What is happening? To understand and solve this problem one needs to understand how Joomla works. Each time the root index.php file is accessed, it looks for the configuration.php. If the config file is found, the site is displayed. If it is not found, it assumes that this is the first time Joomla is run, and therefore the user is redirected to the installation directory to start the installation. So if you have done any changes (renamed or deleted) to the configuration.php file, or if this file for some reason cannot be accessed, Joomla assumes it hasn't been installed, and thus redirects to the installation directory. But in the last step of the installation, you have to delete this directory (otherwise Joomla won't work), and therefore the page is not found. To solve this problem, make sure that configuration.php file can be accessed, or restore it from a previous backup.