If Whatsapp continues to crash or does not load properly after reinstalling the program, you may need to do a software reset. Given that the software has been successfully installed, the issue is most likely within the iPhone system. In such instances, a network settings reset may be necessary to eliminate any network faults that may have led network-based apps to go rogue. Here's how you do it:

1. From the Home screen, choose Settings.
2. Select General.
3. Reset may be found by scrolling down and tapping it.
4. From the list of choices, choose Reset network settings.
5. To continue, enter your device passcode if requested.
6. Then press to confirm that the settings have been reset.