A lost password can be a real headache, especially if it’s the admin account for an installation. It is possible to login without credentials or reset a password for any user from the command line using drush. Drupal.org discusses these operations.

Login

To login to a Drupal installation as the admin user without knowing the credentials simply navigate to your site’s root directory and use drush uli.

From there you can change the credentials or go about your work without changing the credentials.

Reset Password

It’s also possible to change the password for a user using drush upwd.