Hi there! I’m sorry to hear that the Barnes & Noble NOOK app won’t open on your iPhone. To help get this sorted out, could you tell me if you see any error messages when you try to open the app? Also, have you tried any troubleshooting steps so far?

In the meantime, here’s a straightforward way to start troubleshooting this issue on your iPhone running iOS 18.6:

1. Restart your device: Press and hold the power button, then slide to power off. After the phone is off, turn it back on. This can often clear temporary glitches.

2. Check for app updates: Open the App Store, tap on your profile icon at the top right, scroll down to see if the NOOK app has an update available, and update it if so. Sometimes app compatibility issues get fixed this way.

3. Force quit and relaunch NOOK: Swipe up from the bottom of the screen and pause (or double-click the Home button if your iPhone has one), locate the NOOK app preview, swipe it up to close it, then try opening the app again.

4. Check NOOK app permissions: Go to Settings > NOOK, and make sure all necessary permissions (like network access) are enabled.

5. Log out on launch setting: Sometimes toggling this can help. Go to Settings > NOOK and enable “Log out on launch,” then try opening the app again.

If none of these work, the next step would be to uninstall and reinstall the NOOK app. Just press and hold the NOOK app icon until it jiggles, tap the “X” or select “Remove App,” then reinstall it from the App Store.

Does any of this sound like something you’ve already tried? If so, let me know, and we can look into more specific fixes together.