Iphone 5 notifications don't work

Hi guys,

I have an iPhone 5 with iOS 9.3.5 and recently my notifications have stopped working.

If I have any missed phone calls or messages, it appears in the menu that we can swipe from above, but then the symbol that usually appears in the app icon (the red one, with the number of unread messages/missed phone calls) doesn't work, it just doesn't show.

I've already checked settings, I've done a background app refresh, I've turned off the notifications, turned off the iPhone, then on again and then turned on the notifications again, and I can't seem to find a solution.

Can anybody tell me what to do?

Thank you!