You can quickly set a user your new password to the ‘somenewpassword’ text below, assuming that the user login is ‘theirusername’. Change the username and password to whatever you’d like and execute the query.
UPDATE wp_users SET user_pass = MD5( 'somenewpassword' ) WHERE user_login = ‘theirusername’;
The below example will get a list of registered users who are assigned the role of subscriber:
SELECT wp_users.ID, wp_users.user_nicename, wp_users.user_email FROM wp_users JOIN wp_usermeta ON wp_users.ID = wp_usermeta.user_id WHERE wp_usermeta.meta_key = 'wp_capabilities' AND wp_usermeta.meta_value like '%subscriber%' ORDER BY wp_users.user_nicename;