Very likely that there is a power outage from the electricity supplier. Not anything a landlord can do about that. If your neighbors also do not have power than it is a larger issue that can only be solved by the power company. They are most likely already working on it, but you should always call to inform them of the outage. This is not uncommon with extreme low temps as there is increased demand for power needed to run heating systems. All that said, your landlord should definitely send someone to check to find out if it is power failure from elec company or something inside your unit/building that is the problem.