At first make sure you have mysql installed properly. You can ensure it just by checking that whether you can access mysql using mysql command promp. So if you mysql is working then probably it is not loading. For that follow the steps given below
First of all, you must find your php.ini. It could be anywhere but if you create a small php file with the
<?php phpinfo(); ?>
script it will tell you where it is. Just look at the path of loaded configuration file. Common places include /etc/apache/, /etc/php4/apache2/php.ini, /etc/php5/apache2/php.ini or even /usr/local/lib/php.ini for Windows it may be C:\Users\username\PHP\php.ini
Edit your server’s php.ini and look for the following line. Remove the ‘;’ from the start of the line and restart Apache. Things should work fine now!
For windows it will be