To make this short, I live in an apt. and share the boiler with the neighbors our zone was added on to the existing boiler, everything was working fine until some how my thermostat (2 wire) got disconnected. Our valve is open on manual so we only get heat when the neighbor puts there thermostat up. I do not know how to wire the thermostat back. Thank you Bill

I would contact your landlord before doing anything. Your thermostat could have been disconnected on purpose by your neighbor or landlord. Messing with the wiring that does not belong to you can cause a problem with the system that could make you liable. Be safe and contact the landlord.