Thanks for stopping by the Apple Support Communities. From your post, I understand that your Notifications Center does not display any content. If you tap the display while it's open, the Messages app will open, so it appears the iPhone recognizes the notifications are there despite not displaying them. I'm happy to help!
First, force close any open apps: How to force an app to close on your iPhone, iPad, or iPod touch - Apple Support . Then, restart your iPhone: Restart your iPhone, iPad, or iPod touch - Apple Support . After the iPhone has been restarted, check to see if your Notifications Center displays notifications.
If you still cannot see the Notification Center, backup your iPhone using iCloud or iTunes, as described here How to back up your iPhone, iPad, and iPod touch - Apple Support , then reinstall your iOS software. You can do that using the steps under the "Put your device in recovery mode and set it up again" section of If you can't update or restore your iPhone, iPad, or iPod touch - Apple Support .
Cheers!