Back Button doesnt work

When I press the back button I do not return to the previous page, its closed the app.
where am i making mistakes

Its too general Alzmoth, at least provide more info about your code.

You can actually use the NavBar example and you don’t have to specify any back button. Ionic will auto generate a back button for you whenever you push a page.

in ionic 2, navigation works like stack.
If you do not want to exit app set your page to
"this.navCtrl.setRoot(“Particular page to be shown”)"

My problem is my app didnt stacked page.
where is the problem. i cant find