If apps won't open on an iPad because of a small bug or software glitch, the easiest solution is to restart the iPad. Simultaneously hold down the home and power buttons to force the iPad to restart.
If restarting the iPad does not solve the issue, attempt to reinstall the application. First, press and hold an application until all the apps begin to jiggle. Tap the X button on the application's icon to delete the app. Then, open the App Store. Navigate to the app's page, and download it again. Downloading a paid app an additional time should not charge the consumer again as long as identity can be confirmed.
Sometimes, even these steps won't guarantee an app opens. In this case, consider resetting the iPad. A software settings reset can be done in the Settings app. This option keeps all of the user's data and downloads, but restores all custom options. Alternatively, start a full restore. This extensive process removes all traces of user activity and returns the device to its factory settings. After performing a full restore, download the app again and attempt to open it. If it still doesn't open, this indicates an error in the app's coding. Contact the developers to report the issue so that it can be addressed in future updates.