Hey there okan293,
Thanks for reaching out to Apple Support Communities. We're happy to provide some assistance.
To make sure we understand the issue correctly, you're having issues with an app that you downloaded from the App Store? If so, this article can resolve most third-party app issues:
If an app on your iPhone or iPad stops responding, closes unexpectedly, or won’t open - Apple Support
Close and reopen the app
Force the app to close. Then open the app to see if it works as expected.
Restart your device
Restart your iPhone or restart your iPad. Then open the app to see if it works as expected.
Check for updates
To see if updates are available for the app, open the App Store, tap your profile icon, then scroll down to see if updates are available. If updates aren't available for the app, update the software on your iPhone or iPad.
Delete the app, then redownload it
Delete the app. When you do this, you might lose data that was stored in the app. Then redownload the app. Then check to see if the problem with the app is fixed.
If the issue persists with a specific app, we recommend contacting the app developer:
How to contact an app developer - Apple Support
If we did not understand the issue correctly, please elaborate, so we can better assist you.
We hope this helps.
Have a great day!