I have installed wamp on windows 8 and received above error whenever I go to localhost or phpmyadmin. After much searching I found many answers which includes modifying the httpd.conf to
Allow from All
I find the best (and least frustrating) path is to start with
Allow from All, then, when you know it will work that way, scale it back to the more secure
Allow from 127.0.0.1 or
Allow from ::1 (localhost).
As long as your firewall is configured properly,
Allow from all shouldn't cause any problems, but it is better to only allow from localhost if you don't need other computers to be able to access your site.
Don't forget to restart Apache whenever you make changes to httpd.conf. They will not take effect until the next start.
Hopefully this is enough to get you started, there is lots of documentation available online.