iPhone 5 screen stopped working

I'm currently on iOS 9.2.1 iPhone 5. Whenever im in an apps and pressed the notification center through assestive touch, my whole phone will just stop in hat apps, and i cant go back to the homepage. when i locked my screen and it wont appears anything until i pressed the home button and the lock screen button only it back to normal. but i pressed it notification center through the assestive touch it happens again. any solution?