If you lost all your iPhone data after iOS 5 update, inlcuding contacts, SMS, call history, notes, etc. Don't panic. There are two ways for you to restore your iPhone after iOS 5 update.
The most common way that people can think of is restoring your iPhone from iTunes. You only need to connect your iPhone with iTunes, and click "Restore". Your iPhone will be restored from the backup generated by iTunes. This restore will erase all contents existing on your iPhone, instead of the whole backup content. If you don't want to lose the files on your iPhone and restore the content selectively from the backup, you need to switch to the second way.
The second way is to use third-party software, which helps you to selectively restore your iPhone data from iTunes backup, and you can preview the backup content before you decide to restore. If this is what you're looking for, you need to get an iPhone restoring tool first: Wondershare Dr.Fone (Mac) (for Mac users) or Wondershare Dr.Fone (for Windows users). It can do all these for you, no matter you're using iPhone4, iPhone 3GS, or other versions.
Download this trial version below and install it on your computer.
Steps of restoring iPhone after iOS update
Step1. Choose iPhone backup and scan
Install and run the program on your Mac, and you'll get the backup for your iPhone. Choose it and click to "Start Scan" the contents in it.
Step2. Restore iPhone after iOS 5 update
When the scan is over, you can preview all the contents of the backup before restore to decide whether you want them or not. Tick files you want to recover and click "Recover", you can save them all on your Mac, and them put them on your iPhone, which does no harm to your iPhone existing contents.
Not only iPhone, this software also works well for iPad and iPod touch. You can restore them from any backup file on your iTunes.