Car not blowing hot or cold

well if you have no blower fan speeds at all you are most likely looking at the blower motor, located under the glove box. Once you locate it give it a tap and see if it comes on, as for your back window the defrost there is electric and tolaly separate from the front.if the motor comes on it will still need replaceing, this is only a very temp solution, if it dont come on check to see if you have power going to it

Thank you @steven boussey