On my iphone4s I have lost all my contacts and calendar

You found part of support communities that support icloud. Presuming that you knew abut that and your contacts and calendars are in icloud - sign in icloud on the phone and you will get your stuff back.

I had this problem also, and it seemed like my phone wasnt syncing to ICloud. This fixed it.

Settings

ICloud

toggle off your contacts, select "keep on My IPhone", wait a couple of seconds, toggle on your contacts, select "merge"

repeat for anything else that is missing data

Hope it helps