1. Make sure you have an active connection to your mobile network or to a wireless connection; depending on the app, you’ll only receive notifications when you’re connected.
2. If you’ve recently installed an app, open it and, if required, sign in. Some apps require a log-in to their services before they can send you notifications.
3. If you’re not receiving alerts from a particular app, try uninstalling the app, switching your phone off and then on, and then reinstalling the app. Note that some apps are notoriously buggy when it comes to notifications.
4. If you’ve changed your password for a service, make sure you update that password in the related iPhone app.
5. If you can’t access the Notification Center, make sure you’re running iOS 5.0 or later. The Notification Center was newly introduced in version 5.0.
6. If you’re using a Wi-Fi connection, check that your firewall is not blocking port 5223.
If you set an alarm on your phone to wake you in the morning but don’t want to be disturbed whenever an email or message arrives during the night, flip your phone into silent mode, then tap Settings > Sounds and turn Vibrate off in the Silent section. Your alarm will sound, but your phone will neither beep nor vibrate when a notification arrives.