Its getting cold and my car heater is not.

When it was overheating, did you replace the thermostat? Have you checked to make sure the coolant is full? Is the engine operating at a normal operating temp?

It sounds as if the coolant hoses to the heater core have been rerouted to prevent the overheat.
Please make sure the hoses from the water pump are connected to the firewall. (These go to your car's interior heater core)

If not, then the need to be rerouted.
As for the cold air, the air blend door may be broken (or actuator motor).

Good luck.