Can't download an app

I have an issue with the app store. A few weeks ago I tried to update Whatsapp. It didn't update or do anything really. I could still use the app but the update button on the app store had changed to the circle with square inside as if it were updating. This stayed the same for weeks and I couldn't press the circle to resume the download or anything. I just carried on using the outdated version of Whatsapp. But then the app said that version would not work in so many days until the point where it was no longer supported so I had to delete the app. I thought this might work and I would be able to download it once deleted but the app store still has that circle with the square inside. So even though I don't have the app I can't reinstall it. I have tried rebooting the phone numerous times, signing in and out of the app store, turn off and on automatic updates and many other ways people have fixed similar problems. Any suggestions? I know I don't have the latest IOS and I will be updating tomorrow but I'm not really hopeful on that working.