I think if you go into /my documents/my games/galciv2 folder and delete the preferences file (prefs.ini?), it will reset everything to the state it was when you first installed the game. It might be in a subfolder, poke around.
If you understood the above, try playing around with that. (if you didn't you're better off not messing with it )

Someone please feel free to correct me.

heh, wait and make sure it works before you start to worship
there is a galciv folder in /my games though, and there is a prefs file in it somewhere.
not exactly sure what happens if you delete it, but the worst is that you'd get all your settings reset.
if you wanted to get really clever, i'm sure you could open it in notepad and find the section where you botched up the yor and just remove that section.
They really do need a 'reset races to default button' on the race setup screen.
good luck