If you are sure that your car battery is drained, you have to either jump-start it or replace it. In order to make sure you will not encounter the same problem, you also have to find out what caused your car battery do die. It is not very difficult to determine the causes that have drained your car battery. There are certain things you need to consider:
Try to remember when you bought the old battery. The life span of car batteries is between three and five years, so if your battery is older than that it might have died of “natural causes.”
Also, try to remember if you happened to forget the headlights on while the car was turned off. Headlights or other lights in the car can quickly drain the battery.
If you have used the radio or the sound system while the car was off, this might be the cause of your drained battery. Using the sound system for a little while will not harm the battery, but keeping it on for longer is a different story.
Your battery might also be dead if you have not driven the car for a long time. Keeping the car in the garage for long can negatively affect the lifespan of your battery.
Car batteries might also freeze if the weather is very cold.
If nothing mentioned above happened and there is no obvious cause for your battery to die, you need to see a mechanic. Your battery might be drained because the alternator does not function properly.