If you’re like me and you tried the “lost password” link on prestashop’s backend and never received the email, you might try this solution if you have access to the database.  Look in config/settings.inc.php for the _COOKIE_KEY_ as you’ll need that. Run the following SQL and replace the <> variables with your information.

UPDATE employee SET passwd = md5(”<_COOKIE_KEY_><yourNewPassword>”) WHERE email = “youremailaddress”;

hope that helps

credit: nickbartlett.com