300tdi overheated, died, now won't start

Was driving my 300tdi at 70 oblivious to the world and didn't notice the engine overheat until it was too late and the engine died and I notced smoke out the back, Lifted the bonnet and plums of smoke, not good.

Got recovered home tried to start and nothing, cranks but no fire. Could this be a simple head gasket or could I be looking at more extensive failure?

Any help much appreciated

You'll never know until you get the head off. It could be a warped head, cracked block or you might get lucky but I suggest you find the reason it overheated first