In Mobile Phones
If you had to reformat your computer and re-install iTunes how do you sync your iPhone without losing your apps?
After installing iTunes, plug in your iPhone and let it complete any patch updates or system backups. Then, find your iPhone under "Devices" in the left-hand explorer bar, …right-click it, and select "Transfer Purchases." See http://theappleblog.com/2008/07/22/transfer-applications-from-iphone-to-itunes/ for screenshots. ( Full Answer )