Wide Screen Help

Hey there! So. I just got a new wide screen monitor and in an attempt to play Gal Civ using it, I seem to have changed the resolution to a setting outside that which my monitor is capable of showing. Now when I try to load the game only black appears. Is there a way to change the video settings without going in game? All the drivers and what not are up to date, so I'm not sure what's going on. Any help would be greatly appreciated. Thanks!