To resolve the issue of an app not opening on your iPhone, follow these step-by-step troubleshooting steps:

Restart the App

1. Double-click the Home button (or swipe up from the bottom of the screen if your iPhone doesn't have a Home button) to access the app switcher.

2. Locate the app that isn't opening and swipe it up off the screen to close it.

3. Try reopening the app to see if this resolves the issue.

Restart Your iPhone

1. Press and hold the side button and either volume button until the slider appears.

2. Slide to power off your iPhone.

3. After the device turns off, press and hold the side button again until the Apple logo appears.

4. Once your iPhone restarts, check if the app opens.

Update the App

1. Open the App Store on your iPhone.

2. Tap on your profile icon at the top right corner.

3. Scroll down to see pending updates. If the app you’re having trouble with appears, tap "Update" next to it.

4. After the update is complete, attempt to open the app again.

Check for iOS Updates

1. Go to Settings > General > Software Update.

2. If there's an update available for iOS, tap "Download and Install."

3. After updating, check if the app opens successfully.

Delete and Reinstall the App

1. Find the app on your home screen.

2. Press and hold the app icon until a menu appears or the icons start jiggling.

3. Tap "Remove App" > "Delete App" > "Delete" to uninstall it.

4. Go to the App Store and search for the app to reinstall it.

5. After installation, check if the app opens.

Reset All Settings

1. Go to Settings > General > Transfer or Reset iPhone.

2. Tap "Reset" and select "Reset All Settings." This will not delete your data but will reset settings such as Wi-Fi passwords and wallpapers.

3. After your iPhone resets, try opening the app again.

If none of these steps resolve the issue, it might be worth reaching out to the app's support team or checking their official website for known issues.