Pages

I updated the IOS of my IPAD Air2 to version 13.4.1 after doing a backup. But now i cannot open Pages. It keeps telling me that i must “purchase this app to install it”. It tells me to go to the App store but when i go there it tells me that i already have Pages. I also tried to upadate Pages but it just brings me back to that message that i have to purchase Pages. Please help. I have a number of files on Pages and dont know how to get them back. I have tried to restore from my backup but it still has the same problem. Help!