It is necessary to separate the problem of your push notifications not reaching into your device as two different topics.
1. If you are trying to send push notification from the app for the first time and you can not send;
If you are sending push notification for the first time in your app and none of your devices receive a push notification, this problem is caused by the improper uploaded of the app or an internet connection on your device. If the latest version of your app is downloaded on your device and even though you have an internet connection your push notification doesn’t reach to your device, please contact us at firstname.lastname@example.org
2. If you can send push notifications before and if you can not now;
If your app can send a push notification before but it no longer reaches your device even if you send it. This problem is caused by your app not being uploaded on your device, not having an internet connection and changing your package name. In order to learn more information regarding package information, you can read the relevant article What is the Package Name?
When you change your package name, you need to update your app on your device or the Google Play Store so that you can receive a notification.
If your push notification does not reach your device even after you have done all these steps, please contact us at email@example.com.