Greetings, NoniD.283.
I see that the Instagram application on your iPhone isn't working as expected, and I'm happy to help.
If an app unexpectedly quits, stops responding, or won’t open -- These are the steps that Apple provides for applications that aren't working as expected. It appears you only have one step left to use and that would be step 5.
Contact the app developer
If you're having an issue with an Apple app, contact Apple Support. If it's a third-party app, contact the app developer.
Take care!