There's no Assistive Touch on my iPhone

I have an iPhone 3g and my power button on the top broke and is unable to use. I heard there's something called Assistive touch and i can get it by going on settings>general>accessibility but there's no Accessibility option. Is there a way i can get it?

Are you updated to the newest iOS version? Plug your iPhone into iTunes and check for updates.

EDIT: Assistive touch is a new feature in iOS 5.0+ only. The iPhone 3G may not even support iOS 5 because it's outdated.