Changing admin password or even username for magento is not so that hard but a bit tricky.
All you have to gain cpanel access and open phpmyadmin.
Select your database in phpmyadmin and hit the sql tab.
Now write the following text in text area and replace “mypass” with your actual password. Note that x2 is the salt added to password you can change s2 to any other salt as well
UPDATE admin_user SET password = CONCAT( MD5( 'x2mypass' ) , ':x2' ) WHERE user_id =1
For example my salt is tq and my password is super that will go as follow
UPDATE admin_user SET password = CONCAT( MD5( 'tqsuper' ) , ':tq' ) WHERE user_id =1