Cannot Access WP-Admin/Site Broke

I have recently started working on a WordPress site:
http://integration.dahan.com/

Everything was working great and I had customized it how I wanted to. However, yesterday I purchased the domain: coaintegration.com from GoDaddy. I set GoDaddy up to mask the domain but was unable to link individual pages without using the original integration.dahan.com urls. So I looked through the WordPress pages on how to set up a new domain. As soon as I changed the domain in general settings in the dashboard, it broke my site’s layout, theme, and I am no longer able to access WP-Admin.

I downloaded all of the folders and data through FTP a few hours before this happened so I should have all the data. However, the normal things such as renaming the plugins and theme folder did not work. Nor did uploading the files previous to the failure.

I have no idea what needs to be done to restore the WP-Admin and do not want to redo the site entirely as I was using the RSS feed for iTunes podcasts among other things.

Any help would be great, thanks!