Camry 2.2 LE 94 - stopped on highway
 

I have camry 2.2 LE with 165 000 miles on it.
Yesterday I was driving around 70mph on highway when I heard some rattling noise. It lasted for few seconds and then the car stopped.
After that I tried starting it up but the engine wouldn't start....It didn't even spin. I just heard ignition click and that's it.
At first I suspected on timing belt but mechanic disagreed and said it is something far more serious.
Today he emailed me that I'll need to buy a new engine and replace it.
Prior to this event car was running just fine without any symptoms (no overheating, no sounds, no vibrations...).
I am going to see my mechanic tomorrow but want to have some idea what's going on before I visit him.
I appreciate your help.:)