Ok, look in your Apache access log.
left click wampmanager icon -> Apache -> Apache access log
Look at the bottom og the file, if you see a line with a 403 error and an ip address of
::1 you need to do the following.
Edit C:\wamp\alias\phpmyadmin.conf
Change it to look like this :
<Directory "d:/wamp/apps/phpmyadminx.y.z/">
Options Indexes FollowSymLinks ExecCGI
AllowOverride all
Order Deny,Allow
Deny from all
Allow from 127.0.0.1
Allow from ::1
Allow from localhost
</Directory>
so you will probably have to add the line:
Allow from ::1