Just create a file "new_password.php" (or with any other name) inside your drupal folder and access it using browser. It will generate one way encrypted hash password for you.
require_once DRUPAL_ROOT . "/includes/bootstrap.inc";
When you run this code in browser it will show you hash password like
Now you need to update your database table using above hash. Open your database using PHPMyAdmin or Workbench and run the below query.
UPDATE users SET pass = '$S$D95YW4EejaUDPq5nZ7Z2Ljx1Ud4wlN1iTMQdAKton70JcQpCZmrG' WHERE uid = 1;
Now you can access drupal using username as "admin" and password as "123456". Make sure you update password after login to the admin.