Contacts lost in Samsung S3
Sorry to say this, but there isn't any way to do so as far as I know.

What you can do now, is to simply add your Gmail account to sync at-least your old contacts.

If your sync is not working properly, then do the following:


Check that Internet connection is working properly on your phone, by resetting your mobile internet connection.
If above solution isn't working then try restarting your phone after removing your SIM card for at-least 10 minutes.
If the problem still persists then please contact your service centre for further help.