When clickin "home" twice, nothing happens. Could it have gotten disactivated by my kid accidentally?

I have iPod 3rd generation, & when I hit the home button twice, the apps dont jiggle to force close the apps that are running on the background, like I do in my iPhone. So is there a way my kid could have accidentaly deactivated the double tap feature? How can I get it to work without reseting everythig else?