Text messages disappear in Iphone6s

I was texting this morning. I closed my app and now all of my texts are gone. Also everytime I close the app any new texts I've sent are gone upon reopening. I'm not getting notified of new texts received, and when I send a text I get the blue bar saying the texts are still sending even though the recipient has received the text. I have an Iphone6s ios 11.4.1 and I have 48.9 GB free out of 128. I have turned the phone on and off several times and still nothing. AT&T is my carrier. Can anyone help me please?