I changed the root password to test and now I cannot login in phpMyAdmin page in XAMPP. I looked for help here and here which basically says changed config.inc.php>
If you are facing this issue after changing password in phpmyadmin, paste the old password (passwd before change) in xampp\phpMyAdmin\config.inc.php :
xampp\phpMyAdmin\config.inc.php
$cfg['Servers'][$i]['password'] = '**old password here**';
Hope, it would work :)