You can actually restore them from iCloud if you have ever synced them with iCloud. But if you have not, you do not have to be so worried, there is still solution available. You can google a program called Dr.Fone. I had exactly the same problem with yours several days ago, and with the help of it I finally found my contacts back. You could download a trial version of the program to scan iTunes backup of your iPhone 4S and to check whether the found contacts and pictures are what you want to find back. For more, you could learn here: http://www.wondershare.com/disk-utility/restore-wiped-contacts-on-ios-6.html. Wish you good luck.