How to Uninstall and Reinstall an iPhone App
The iTunes App Store gives iPhone users access to thousands of third-party applications. These apps can greatly expand the usefulness and functionality of an iPhone. Unfortunately, some users may experience occasional problems with an app and it may be necessary to uninstall and reinstall the app to get it to function properly. Uninstalling an iPhone app and then reinstalling it can be done in a few simple steps using the media management application in iTunes.
Connect the iPhone to your computer using the USB cable supplied with the phone. Launch iTunes by double-clicking the "iTunes" icon on your computer desktop.
Click on the name of your iPhone, which will appear under the "Devices" heading. Click the "Apps" tab to view all of the applications installed on the phone.
Remove the checkmark next to the application that you want to uninstall. Click the "Apply" button to apply the changes and uninstall the application.
Recheck the box next to the application that you just uninstalled. Click the "Apply" button to apply the changes and reinstall the application.
Click the "Eject" button next to the iPhone's name in the "Devices" pane and then disconnect the iPhone from your computer.