Error in admin.php once logged in – No wodpress screen loading

I logged in from my wp-login.php page and came up with the following error.

Warning: require_once(/home/pjdcreat/public_html/site/admin.php) [function.require-once]: failed to open stream: No such file or directory in /home/pjdcreat/public_html/site/wp-admin/admin.php on line 12

Fatal error: require_once() [function.require]: Failed opening required ‘/home/pjdcreat/public_html/site/admin.php’ (include_path=’.:/usr/lib/php:/usr/local/lib/php’) in /home/pjdcreat/public_html/site/wp-admin/admin.php on line 12

How do I get this error to disappear and just get the WordPress interface to load correctly?