Permissions problems

I seem to have screwed up my site after trying to sort out the following issue with WP Super Cache.

I got the following message so tried to edit the permissions on my site.

Warning! /home/andym/public_html/blog/wp-content is writeable!

You should change the permissions on /home/andym/public_html/blog/wp-content and make it more restrictive. Use your ftp client, or the following command to fix things:

chmod 755 /home/andym/public_html/blog/wp-content/

So after doing this I’ve been unable to get into my blog with the following error.

Forbidden

You don’t have permission to access /blog/ on this server.

The Wp-Content folder is at 775 as are all the sub-folders. I’m at a loss as to why this won’t let me in. I’ve removed the Wp-Cache plugin and taken out the sections from the .htaccess file.

Really worried I’ve lost all my posts since 2007. Any help would be most appreciated. Can I simply re-install the software on the server and add the content back?

Thanks