I just restored as a new iPhone with iOS 4.3.2 and found I was missing a bunch of Settings, including the top level Personal Hotspot, Notifications, and VPN tabs. I use these a lot so needless to say it was disconcerting. After a bit of deduction, I was able to get them back. Follow on after the break to find out how...
Notifications controls which apps can send push notifications. Since I hadn't enabled any push apps, I installed a Twitter client, it popped up the allow push dialog, I accepted, and the push panel appeared in settings. One down.
VPN and Personal Hotspot are enabled by the carrier file which is downloaded and updated separately (so iPhones can work on different carriers, with the features those carriers choose to allow). In addition to being top level, they're also typically available under General, Network Settings. The problem was I didn't have Network Settings either. A reboot fixed that.
Once Network appeared I went in and my iPhone began to detect the carrier file and settings, and then Hotspot enabled and appeared. Toggling VPN on in Network also forced it to appear top level.
And then everything was back to normal.
Have you ever lost options in Settings? If so, let me know what if anything got them back for you!