My customer called me today to report that he can't login to the admin portion of the site. Instead of seeing a login box, there is a page full of raw php code, followed by an error code:
here is the code at the bottom as it appears:

Fatal error: Call to undefined function: zen_get_top_level_domain() in /home/content/t/e/r/terrysmith8499/html/admin/includes/init_includes/init_tlds.php on line 13

I've tried uploading fresh copies of admin.php, index.php, and the init_tlds.php file mentioned in the error code.

Any suggestions? I've out of ideas.