You won't be able to unlock it. It's only usable for parts at this point. OR you can try to "do the right thing" and turn it in to the police or the carrier. HOWEVER Verizon might not take it. I'm also told Apple will not take lost or stolen phone and they advise you turn them in to the police. Now I'm not sure how much actual investigations the police will do either with all the major crimes that go on, such as murder and bank robbery, assault, etc Stolen phone might not be too high on the list.
