car cannot start

99 camry ce.

I parked my car in the parking lot for three days and today I couldnot start it. When I turned to "On", the light in the car didn't come on, and I even couldn't use power window and couldn't lock the four doors from inside. Also, I heard click under the hood.

I called AAA to jump start it and it worked fine. The thing I was confued about is some people say that's because I didn't turn off the headlight when I turned off the engine last time. But seems to me all headlights came off automatically when you turn off the engine and they should not consume power during this period.

If it's not the problem of headlights, then maybe something wrong with my battery. It does have small part of corrosion on the battery, but i don't know how much it contributed to this no-start problem.

Thanks in advance for your suggestions!

========================================================== The owner's manual recommends you turn off the headlights manually if the car will not be used for three days. While it is true the headlights turn off automatically, the mechanism is controlled by a relay which does consume a small amount of current to keep the headlights off even though the headlight switch is "on." Corrosion on the battery should be cleaned off to help ensure best conductivity and minimize damage to the connections. It may also be helpful to put the battery on a charger to bring it back up to full charge. Batteries can sulfate more easily when fully discharged such that they subsequently do not hold a charge as well. See how well the battery turns over the starter motor when fully charged after sitting over night. If it spins sluggishly, would probably be time to replace the battery.