If you know your username and the email account in your profile, you can use the “lost password” function –
- Go to your WordPress Login page (something like http://yoursite.com/wordpress/wp-login.php)
- Click on lost password
If you can’t use this method, you will need to modify your database.
Ask your host what MySQL administration tools they provide. Then run the following query, entering your own choice of password.
UPDATE wp_users SET user_pass = MD5("new-password") WHERE wp_users.user_login = "admin";
You can now login using the new password.