i have iphone 4s,icloud locked am trying to contact with owner to give him back or unlock it he do not want to talk is gsx is helpful in this case? owner not interested in phone!!!!!

It is between you and him, Apple will not help you. So if he does not want too the phone is useless to you, I would advise you to stop bothering him, it's a bit tacky, don't you think?

Unless the previous owner will sign out of iCloud/Find My Phone on the phone or erase it and remove it from their account at iCloud.com, there is nothing you can do.

GSX is only for employees of an Apple-authorised service company. A private individual cannot access it; but in any case it's nothing to do with your phone. In the situation you describe the phone is permanently useless.

The people who sold you the phone are responsible for selling you useless merchandise and you should approach them for a refund.

GSX is Apple's facility for technicians in Apple-authorised service service centres to allow them to carry out repairs without invalidating the warranty, obtain spare parts, and get easy contact with Apple technicians if they have a problem. Please see this page:

http://www.macworld.com/article/2043155/how-to-become-an-apple-certified-macinto sh-technician.html

I don't know whether anything has changed in the three years since that article was posted; but in any case none of this is relevant to you.