I’ve seen a huge spike in traffic on my site searching for iOS lost contacts. We now have 6 different solutions to restore your contacts.
Thought I’d post something specifically regarding iOS 5, and some solutions that are out there. Personally I had no problems upgrading, and think losing contacts may just be because the initial “sync” hasn’t gone through yet (remember an iOS upgrade resets your phone to base iOS 5, then imports your information after).
I just upgraded my iPhone 3GS to iOS 4 (iPhone OS 4) and lost all my contacts. Initially they were there and all was well, but then they all disappeared.
I even had to enter my voicemail PIN for the first time in years (I have never done this since first setting up my original iPhone years ago).
The fix? I’m not sure