If you need to jump start the car then the battery may be fully charged but it is defective and needs replacing. A full charged battery will read 12.6 volts at the posts with the engine not running. 12 volts indicates the battery is only 25% charged.
Low/bad battery, bad battery connection. If the battery isn't getting fully charged you might not be able to start. If it isn't getting charged, check the alternator.
is your battery in good condition and fully charged? is your starter good?
As long as the battery is fully charged it will start no matter the condition of the alternator. Eventually the battery will run down if the alternator is not keeping it charged.
probably the starter
It will start if there is enough charge in the battery to turn the engine over. However if the alternator is weak then the battery will not be charged fully.
Does it turn over? Does it have spark? Does it have fuel?
Fresh fully charged battery and fresh gasoline
Yes they could be cleaned and battery charged
YOU HAVE TO TURN IT ON Actually, I learned this past week that if it is a gel type battery, you can get a false positive on the battery, so it looks like it is fully charged but actually is not. You can take the battery to your dealer to see if he can charge it or you need a new one.
In most cases a new battery will be charged enough to start the vehicle
It could be a number of things. First check that the battery is fully charged.