If you go to start your car in the morning and it just won't turn on, there are many reasons this may happen. Most of the time, a car that won't start is caused by a dead battery. Check your car. Did you leave the headlights on? Was a door not shut all the way, leaving the interior light on all night? Was the key in the ignition? Perhaps you didn't turn it all the way off.
Unfortunately, this sort of thing may happen from time to time, but it is an easy fix if you know an oversight is to blame for the dead battery. All you will need to do this is a set of jumper cables and another vehicle or a portable battery charger, which you can find at any auto parts store. For the sake of argument, we'll say you found a neighbor to give you a jump. Make sure your batteries have the same voltage. Cars and small trucks typically have 12-volt batteries while larger trucks may be equipped with 24V batteries.
Have them park their vehicle so your engines are as close together as possible, shut off the engine of the working car and pop both hoods. Take one end of the jumper cables and attach the red clamp to the positive terminal on the dead battery, they attach the other red clamp to the positive terminal of the working battery. While you're there, connect the black clamp to the negative terminal of the good battery. Then take the remaining black clamp and attach it to the frame of the car with the dead battery. Do not attach it to the negative terminal, as it may spark, which can cause an engine fire or even explode the car battery.
Once this is done, have your neighbor start the engine of their car and let it run for a few minutes to charge up their battery a bit. After a couple of minutes have passed, hop into your car and crank the ignition. It should start right up, but if not, double check the connections and try again. As soon as the engine starts, you should disconnect the jumper cables, starting with the negative, or black, cables and then moving on to the red ones. Take care to not touch the clamps to any metal surfaces or each other while doing this.
Now that your car is running, leave it be for at least 20 to 30 minutes. This will charge your battery back up. You should make sure to shut off any accessories, such as lights, radios and the air conditioner. Otherwise, they will use some of the engine's power output and it will take longer to recharge your battery. After the battery is back in working order, your previous oversight will be amended and you should not have trouble again.
If you do find you car is dead again soon after a jump, you may be dealing with a faulty alternator or starter, which will need to be replaced. It could also be due to bad connections on the battery terminal. In this case, you can clean them off pretty easily with a bit of baking soda, some water and a wire brush. Just be sure to wear protective gear when dealing with corrosive material. As the name suggests, it is highly corrosive and can burn your skin.