Engine Lock

What is your question?

Yesterday morning went to start my car and nothing happened. Since I had bought a new battery from Sears 2 weeks ago and it didn't start even after a jump II had it towed to Sears. After inspecting it they said the engine locked and there was no oil it. So I would have to have it towed out of there shop and taken somewhere else. Does this mean the engine will need to be replaced, what might it cost, and is it worth it on a car with 100,000 miles?