In the Zen Cart original files zip, there is a /zc_install/sql/mysql_zencart.sql file.
Inside that file are several lines that begin like this:
Code:
INSERT INTO countries ...
So, the answer to your question is this:
1. Go to Admin->Tools->Install SQL Patch
2. Type in:
Code:
TRUNCATE TABLE countries;
and click Send. This will delete your existing countries records so duplicates aren't created when inserting the master list.
3. Copy the list of INSERT INTO countries statements from the mysql_zencart.sql file to your computer's clipboard, and PASTE that into the SQL Patch window, and click Send.
Done.