When installing multisite you have to 'remove www' from site URL, can't undo!

This is my third try at getting some help for this. (previous post here – http://wordpress.org/support/topic/adding-multisite-removed-www-from-my-url-causing-broken-links?replies=2 )

When I was intalling multisite I was instructed to remove the www from my site URLs, i did.

But now I realise this has caused a lot of internal and external broken links. Last time I posted on the forum was told to add a 301 redirect to my .htaccess file, which i did but this just means all the links now lead to the homepage not to where there were supposed to.

this is the code i added:
# Getting rid of the WWW in front
RewriteCond %{HTTP_HOST} ^www.dropdeadgorgeousdaily.com [NC]
RewriteRule ^(.*)$ http://dropdeadgorgeousdaily.com/$1 [L,R=301]

I need to either find a way to make these redirect to the non www version of the pages they originally pointed to, or get the www back in the URL.

I know usually you would just add it back in the admin panel but this is greyed out (my multisite set up is subdomains not subdirectories, happy to even change that back if i can).

Help please this is very important.