How can I recover iPhone data lost after iOS upgrade? I've had my iPhone 4  for about 3 months and when I connected it to my computer today I was prompted to update the iOS, so I did. But somehow I didn't realise that it meant I was going to need some kind of password once the update had been downloaded etc... having failed to remember it after a few attempts I simply left iTunes to get some troubleshooting advice. When I got back it seems that the password prompt had disappeared and my phone seems to be back to its original settings.

How can I restore the data that was on the phone?
Right click your iPhone in your iTunes' sidebar, then select "Restore from Backup". iTunes should ask you now what backup you want to restore from, just select the latest one (should be preselected) and it should start restoring all you data.