Database password changed and I am not able to access my site I am using xampp for the hosting for my drupal site
I started with no password for the database root, and I used this database in the installation process of my drupal site where user name is root with no password.
Then I changed the password of the root from the xampp local host. Now I am not able to access my drupal site any more, and I don't no from where I can configure the password of the database for drupal. 
How can I solve this problem?
You can edit settings.php (located in sites/default) to change database information like username and password.