wp admin and Dashboard functions

I modified by accident a php (possibly an index php file) in my control panel and now every time I click to go to the dashboard area I am getting an index of wp-admin and clicking one of the these items gives me an error messages like this one:Fatal error: Call to undefined function _deprecated_file() in /home/agbeatin/public_html/wp-admin/admin-functions.php on line 12.

Someone please help

Thanks in advance,

astorgood1