If you don't have a heater you can heat your room without a heater by opening curtains and allowing sunlight to get into the room, use candles safely, seal doors to keep cold air out.
You can also use a humidifier to heat the room as the humidity will increase the room temperature.
Also electronics can help put out some heat.
You can also sleep under the covers with your head and use your own breath to keep your body warm.
You can heat your house without electricity by using a gas or propane stove or a propane or gas heater that requires no electricity.
Also you can use wood stoves or coal stoves to heat your home without electricity.
If you have a fireplace then you can also use your fireplace with wood if it's a wood fireplace or if your fireplace is gas then it will usually still work without electricity but the blower won't work.
However some gas fireplaces may require electricity to light unless it can be lit with just a lighter or match.
To keep your house warm in the winter without electricity you can use your gas or propane stove if you have one.
The stove can be lit with matches or a cig lighter or use a Kerosene or propane heater that requires no electricity.
If you have a wood burning stove then that would be a good way to keep your house warm in the winter without electricity as well.
Also open curtains and blinds to allow plenty of sunlight in and keep moving.
If your house is too cold then consider getting into your car or vehicle and even sitting in it in your driveway as the sunlight can heat up the vehicle.
Or drive around town with the heater on until the power comes back on.
Also use more blankets than normal to stay warm.