Point CSS Back To Correct Location

I am using a Nimubus theme and I foolishly changed something on their Control Panel that “broke” my site. I can pull up the site, but all the styling is missing and I can’t even log in to wp-admin (it shows a 404 error).

I found that if I view page source and copy/past it into Dreamweaver that if I correct the references to the CSS and I switch to Live View, the site looks exactly as it’s supposed to.

Now, if I could only find the file in my WP install to update this information to. there does not seem to be an index.html, so where can I update this information so I can get back to working on my site?