How to find out the username and password for mysql database
Go to this file in: WampFolder\apps\phpmyadmin[phpmyadmin version]\config.inc.php
Usually wamp is in your main hard drive folder C:\wamp\
You will see something like:
$cfg['Servers'][$i]['user'] = 'YOUR USER NAME IS HERE';
$cfg['Servers'][$i]['password'] = 'AND YOU PASSWORD IS HERE';
Try using the password and username that you have on that file.
Assuming that the user you are using in phpmyadmin has the necessary privileges, you can run this query to change the root password:
UPDATE mysql.user SET Password=PASSWORD('MyNewPass') WHERE User='root';
FLUSH PRIVILEGES;