My installshield is in japanese. how do I change it back to English?

i took my computer to a repair store on base when i was stationed in japan. ive since returned to the states. im trying to install cd software now and my installshield wizard is all in japanese now. i guess that japanese repairman changed the language somehow or maybe installed some language pack i dont know about. i only see the japanese text when it asks me to install a new version of apple software update or the new version of quicktime. how do i change it back to English?