Just for future reference, in all probability, you disconnected the iPad/iPhone before iTunes had restored everything. On the pc, at least, Apple's done a poor job of telling you when the upgrade is done (it doesn't). After the firmware upgrade, but before the actual restore of apps/music/videos/etc., the device appears functional, and iTunes doesn't appear to be doing anything. At this point, many people probably think that the upgrade is complete, and disconnect and start playing with it. Unfortunately, iTunes actually hasn't finished the restore, and disconnecting will result in an empty device. If you leave the device connected and wait a long moment (be patient!), iTunes will pop up a tiny dialog box saying that apps are being restored, and this restoration can take an hour or two, depending on how much stuff needs to be restored.