The breather pipe coming off wouldn't cause the engine not to run but from what you've put in your question I would have to say that it WAS the headgasket.
Why do you say that it isn't the head gasket?
Remember the water leak could be internal into the combustion chamber and been burnt(evapourated) it doesn't need to be external. Also the fan may not be working cause the fan switch needs water to function correctly hense the water being used up in the combustion chamber.
Have you checked your oil to see if it has emulsified with water? Another sign of the headgasket being gone.
Ian, December 2006
