The notification log – where you can view deleted notifications – is only available on Android 4.3 Jellybean or above. For the purposes of this walkthrough, we used stock Android Lollipop.
1. Long-tap an empty space on your Android home screen, then tap Widgets.
2. Swipe left until you get to the Settings shortcut widget.
3. Long-tap the widget until your home screens appear, then drag it to a home screen of your choice.
4. In the Settings shortcut menu that appears, scroll down and tap Notification log.
5. A Notification log shortcut will appear on your home screen. Just tap this, and you’ll have access to your notification history.
Get the Notification log widget on your homescreen, then tap it to see your deleted notifications. Once you’re in the notification log, you’ll see active notifications in white, and notifications that you closed in gray. You can tap the gray notifications just as you would normally, and you’ll be taken straight to the source of the notification.