Sometimes after synching my iPhone (and occassionally my iPad) with iTunes I find that the sync has failed and various apps have not been updated.
As a result various apps can not be opened in the usual way.
The usual solution is to resync with iTunes. Sometimes though this isn’t possible, you may not have noticed the error message on the front of the phone.
The various apps that failed to update, will then fail to start, either by tapping it on the home screen, or through the multitasking bar.
You can tell which apps have failed to update as they will be in shadow and have an empty installation bar. In the above screenshot you can see that Podcasts and Flipboard did not update correctly.
In the past I have had to delete the app and reinstall it. Fine for some apps, but if you are on 3G or have configured the app then this may not be an option. With really large apps, it might not be possible to redownload it on a 3G connection.
As a result you probably think you can’t use the app. I have found a workaround that will work until you get a chance to resync with iTunes.
Search for the app in Spotlight. Swipe right from your first Home screen. Enter text in the search field. In this example I have typed Flip for Flipboard.
This will allow you to run the app, even though you can’t access it through the home screen.
Should point out that if you do a hard reboot of the device, you won’t be able to do this.