If your root directory changed, then you also have to edit Apache's ini file to change the Document Root.
Here is an example copied from http://line-in.co.uk/virtual-hosts-mamp-osx/
<VirtualHost *:80>
DocumentRoot "/Path/To/New/Document/Root"
ServerName line-in.co.uk
<Directory "/Path/To/New/Document/Root">
Options All
AllowOverride All
Order allow,deny
Allow from all
</Directory>
</VirtualHost>