My iPhone just lost all of my contacts and calendar entries, except for 5 contacts that I haven't used in years and actually deleted a few months ago. It also lost my saved player info for at least one game (Infinity Blade II).
I didn't change anything or do anything to my phone; it just suddenly doesn't have any of this information. I still have all my apps, most of which seem to be fine, and I still have my recent calls information, but there are no names associated with the numbers.
What could have caused this and how can I get everything back?
EDIT: I tried restarting my phone. That didn't seem to help. But, here it is, 15 minutes later, and almost everything is back. I'm still missing a couple of contacts and my game profile.
EDIT 2: What I would still like to figure out is what happened. The answers are all focused on backup & restore options. None of them addresses what might have gone wrong or how I can prevent this from happening again in the future, which is the real point of this question.