How come my iPhone doesn't tell me when I have a text message!

So I have an iPhone 4S and whenever I get a text message it rings or vibrates but recently when I get a text message my phone doesn't tell me. The only way I know is I have to go to my messages and check if that makes sence. If someone texts me my iPhone wont tell me or anything I have to go to messages. I don't get why? It was working fine like half an hour ago and then all of a sudden it does this. Can anyone help?

Try going into settings > notifications > messages > notification centre: on + banners