This is quite common problem and I found a lot of tutorials to help me solve it, although, there is one additional problem with my case...
This is my config settings
after changing the root password you must first enter the following in mysql console:
FLUSH PRIVILEGES;
before the changes will take effect
Do this by openening a terminal/command console and navigating to your mysql.exe example: C:\wamp\bin\mysql\mysql5.5.24\bin\mysql -u YOURUSERNAMEHERE -p
If you have fiddled with your root account and can no longer access it see the following link for resetting your root account:
http://dev.mysql.com/doc/refman/5.0/en/resetting-permissions.html
After this it should work fine as per your config.inc.php file