If you are having issues with phpmyadmin authentication in cpanel, you will need to do the following:

1) Reset the root MySQL password through WHM. In most cases this should provide access again.

2) If the above does not work, then you will need to ssh into your server and verify that the phpmyadmin file has not been truncated. To do this, you will run the command:

ls -l /usr/local/cpanel/base/3rdparty/phpMyAdmin/config.inc.php

If this command shows that the file is zero bytes, then you will need to do the following:

1) cp /usr/local/cpanel/base/3rdparty/phpMyAdmin/config.inc.php.in /usr/local/cpanel/base/3rdparty/phpMyAdmin/config.inc.php

2) Edit the new file and replace “__MYSQLHOST__” with “localhost”. You may also need to reset the mysql root password through WHM again.