Iphone4 Restoration

Good Morning,

I have an Iphone4. I made the mistake of attempting to sync it without realizing that I had inadvertently selected my wife's Iphone3 mode. Seemingly, all of the features/apps, pictures, contact information, info on notepads added since July 1, 2011, have been removed. Primarily, I would very much like to know what to do to restore the original settings of the Iphone4. Thanks.