If your WhatsApp app is not opening in your iPhone, it can be a hassle. There are a few things you can try before giving up and uninstalling the app altogether.
Restart Your iPhone: The easiest thing you can do is to restart your iPhone. This often solves small issues with apps like WhatsApp not opening as intended. Simply hold down the power button until you see the ‘slide to power off’ slider appear, then slide it off. Once your device is off, press the same button to switch it back on again and see if this solves the issue.
Force Quit the App: If restarting your phone did not solve your WhatsApp opening issue, then you should try force quitting the app itself. To do this, double-click on your home button to open the recent apps menu.
Find and swipe up on WhatsApp in order to close it completely, then try opening it again from your home screen.
Check Your Network Connection: If force quitting did not work either, then you should check that you have a stable and reliable internet connection. Of course, an app like WhatsApp needs an internet connection in order to function properly, so make sure that you have one by checking that Wi-Fi or cellular data is available in areas where you are trying to use the app from.
Update Your iOS Version: If all of these options fail, then you should check that your iPhone is running on the latest version of iOS software available for it. To do this go into Settings > General > Software Update and see if there are any available updates for installation. If yes, then install them to ensure that all of your apps are working optimally on their required versions of iOS software.
Conclusion: In conclusion, if Whatsapp is not opening in your iPhone then first try restarting your device and force quitting the app itself before checking for network connection and updating iOS software if need be; as these steps can solve most minor issues with apps not functioning correctly on iPhones.