Do you have a backup of the theme? If you do, you could try restoring it.
I don't know where they have ANY of these files locally. As far as they know they don't have any at all. The only way they ever edit the site is though the wordpress dashboard, and they aren't aware of any specific files that they actually have control of. I am getting in contact with the person who set this site up for them in the past.
Also thanks for the help so far, both of you. Wish I could give more definitive answers, I just don't really know much about what they have here, just trying to help them figure it out.