How do you survive in a situation when a major crisis occurs and leaves everybody without electricity for months or even years?

Electricity has only been a common household item in the last 50 or so years.
Before that, people had survived since the beginning of time just fine.
This means that a lack of electricity for any duration of time is something that can be overcome but for most people living a Western country, the loss of power means the complete loss of normalcy as their lifestyle is so dependent upon the grid’s constancy that they do not know how to function without it.
How do you cook a meal if your gas stove has an electric ignition? How do you keep warm if your wood heat is moved through ducts by an electric fan? What do you do with a freezer full of expensive meat? How do you find out what is happening in your area with the TV and radio silent? What will you drink if your water comes from a system dependent on electrical pumps?

These are questions that both the Red Cross and US Federal Emergency Management Agency are asking people to seriously consider (you know things are serious when the Government is asking people to think!!!!)

There are five primary areas that are easily disrupted if the power goes off. Each of these is critical to daily survival so when making preparations for emergencies keep these in mind. In order of importance, they are: light, water, cooking and heating/cooling.

Lighting

It wasn’t too long ago that people were active during the day and simply went to sleep when the sun went down. Candlelight dinners were the norm. So candles or oil lamps and matches are one option. Stock up on oil and have enough candles to get you through the catastrophic event. However they are limited in quantity. After a massive Collapse of modern civilization you probably will need to learn how to make candles or lamps by yourself from natural products like beeswax, animal fat, etc.

Another option is to purchase a couple of solar or mechanically powered torches.
I have several of these and you can never have too many.

Water

If you have a rainwater tank, no electricity means that pumps would not work to bring the water to your tap.
 Sure, having a generator would be handy for a few days, or as long as you have fuel.
The easiest way to guarantee quality water is to store it. The important question is: how much? Both Red Cross and FEMA suggest a minimum of one gallon per day per person. This is an absolute minimum, and covers only your real drinking and cooking needs; bathing is out of the question. Another question is: how to get fresh water then the storage is empty? You will need to find a source of water (it must be filtered and purified before use).
Possible sources of water include installing a rain water tank (and hope there isn’t a drought!), collecting water from an unpolluted stream/river or having a well drilled pre-collapse(can be rather expensive and you have to be in the right type of area).

Cooking

You could quite easily cook a meal using a little portable gas stove – either a barbeque style apparatus. But you’d obviously need gas. Outdoor cooking of all kinds, including grilling and barbecuing, all work during surviving situations, provided you have the charcoal or wood (and matches!) needed to get the heat going. Never use these devices in a confined space, as they emit carbon monoxide!

Not having electricity brings the added difficulty of food storage. The old time refrigerator is a round hole three feet deep. Dig it in your yard (or special place in your bunker) line it with plastic and place a hard cover over it. This hole will keep food from spoiling due to its lower temperature. Most foods would have to be non-perishable, pantry items. For meats you could salt and dry them and you could plant some fruit trees and grow your own vegetables (& herbs).

Heating and cooling

All of the heaters obviously need fuel. It can be woodstoves, propane heaters, kerosene heaters…

One of the most efficient ways to heat is something else we have forgotten in the past 50 years—close off rooms that are not being used.
You can minimize the heat lost in the closed room so you actually wouldn’t use that much fuel on heating.

Solar heat can be “grabbed” anytime the light from the sun hits your house. Even in the dead of winter, the south-facing walls will feel noticeably warmer than the shaded north-facing ones(or visa versa if you are in the Southern Hemisphere).
You can “store” the sun’s heat in any surface. Ceramic floor tiles, for instance, are excellent at retaining heat.
So will a flat-black painted covered plastic trash can filled with water. If these surfaces are exposed to sunlight, say, indoors next to a south-facing window, they will absorb heat during the day. At night, with the window curtains closed, the surface will release heat slowly and steadily into the house.

The best heat though comes from a quality wood stove and dry, hard firewood.
We have two woodstoves and they heat our 5 bedroom house extremely well even in the coldest of winters.
We burn a mix of pine and elder and the heat we get off these woods is second to none.
Also by having a wet-back hook up to one of our stoves we have a constant supply of hot water.