Q: My PC crashed and I lost all of the data in my iTunes library, including the apps that I bought from the iTunes App Store. I don’t have any back up files for these apps, and now I’m trying to update my iPod touch to the 2.2 software and I want to be able to get all of my applications back after the update. Am I going to have to re-purchase all the apps I already bought from App Store and sync them all over again?
A: Under normal circumstances, upgrading the firmware on your iPod touch will not remove any of the applications from your device, since it does not actually erase any of your data in the process.
However, it would still be a good idea to have a backup of your applications in your iTunes library. The good news is that it is relatively straightforward to do this, since iTunes provides the ability to transfer any purchased content on your iPod touch back into your iTunes library automatically.
To do this, simply ensure that your computer is authorized for the same iTunes Store account that you originally used to purchase these applications. You can do this by choosing Store, Authorize Computer from the iTunes menu and entering your iTunes Store user ID and password.
Once you have confirmed that your computer is authorized, simply connect your iPod touch to your computer, and select File, Transfer Purchases From (your iPod name) from the iTunes menu. iTunes will go through your iPod looking for any content stored on it that was purchased with an iTunes Store account on your computer, and transfer all of the content back into your iTunes library. This includes not only any applications you have purchased, but also any audio or video media content.
One final note: Although it should not be necessary if you follow the above steps, the iTunes Store does permit you to re-download any applications you have already purchased at no additional charge. Simply attempt to buy the application as you normally would, and iTunes will not that you have already purchased it and offer you the option to re-download it for free.