Add Customer - Call to undefined function w/ blank page

Add Customer in Admin module is installed on a 139h cart

When trying to add a customer a blank page comes up. In the cache folder the debug file says this.

PHP Fatal error:  Call to undefined function  zen_create_random_value() in /home/username/public_html/admin/add_customers_backend.php on line 547

I've looked through language files for blank lines at the bottom of the file and closed any blank lines that I found. This didn't help.
This is what is on line 547

$customers_password = zen_create_random_value(ENTRY_PASSWORD_MIN_LENGTH);

Any ideas on what to do with this?

thanks

The file admin/includes/functions/password_funcs.php should have a "zen_create_random_value" function. You should check your copy of this file and restore/merge from a known good copy of your version of Zen Cart.

Thank you very much swguy. That's exactly what it was. I have no clue how that file got changed.