Installed base them NineSixty - where is it?
If you have access to the database, check the "system" table of your drupal database and look for a record with the "name" ninesixty. That row will also tell you the path to the theme.

If you have phpmyadmin via cpanel or something similar you can just browse the system table.

Otherwise you could use this SQL (if your database is using a prefix it will be slightly different a the prefix will be appended to the table name "system"):

SELECT * FROM system WHERE name = 'ninesixty';


and that will give you all the info about your ninesixty theme.

Another way is to search your file system for the word ninesixty, which I imagine won't be anywhere except for the theme and maybe your base theme.