If for some reason you can't remember your Wordpress password and you can't use the "lost your password" function that comes with Wordpress, due to problems with email, then you can use the following SQL command to reset your password.
UPDATE wp_users SET user_pass = md5('newpassword') WHERE user_login = 'admin';
This can be useful if you have a local web server that you are trying things out on before they go live on the Internet. These servers often don't have access to email as they are just testing platforms and will therefore fail if you try to use the "lost your password" function.
This command has been tested on Wordpress version 2.6.2.