Joomla admin password is stored in mysql, so it can be changed easily by running a simple mysql query.
If you have a cPanel account, use the phpMyAdmin to reset the password. Select the Joomla database and run the following query.
UPDATE `jos_users` SET `password` = MD5(‘newpass‘) WHERE `jos_users`.`username` = “admin” ;
“newpass” – replace this with the new password you wish to use.
“admin” – replace this with your username.
and submit the query.Now you should be able to login to Joomla admin page with the new password.