First change root password (both) using phpmyadmin
Then after you change it, it will send you an error message
Open this file
C:\xampp\phpMyAdmin\config.inc.phpChange the line 19
$cfg['Servers'][$i]['auth_type'] = 'config';To
$cfg['Servers'][$i]['auth_type'] = 'cookie';And also line 23
$cfg['Servers'][$i]['AllowNoPassword'] = true;To
$cfg['Servers'][$i]['AllowNoPassword'] = false;After that restart you apache
Done