Is it cranking or not cranking? It could be spark plugs that are getting old or spark plug wire problem . Your battery goes down because you try to start the engine to many time. is this a new car with electric anti corosion system this system will drain your battery. the problem is the charging system The alternator may need to be replaced. (A local mechanic or parts shop may sell you a rebuilt one and give you some money back for the old one.) It may just be that the alternator belt needs to be tightened. If you're able to turn the wheel (belt drive) on the outside of the alternator with your own hand (while the car is not running, of course), then the belt is too loose. If you have a crowbar and a wrench and a little bit of muscle, you can tighten the belt yourself.
is the battery dead? if not check your connections and/or for corrosion
battery is low. get a boost or charge the battery.
my alarm keeps going of and wont start.
Try getting a boost.....that'll help
Weak car battery
The battery is dead - you would need to boost the vehicle in order for it to start , but once you shut the vehicle off it will not start again without boosting or hooking it up to a battery charger
How is your battery ? Try a battery charger , battery jumpstarter pack , or a battery boost and see if it starts . ( also, it could be a battery cable connection )
It could be the voltage regulator.
you have a loose or dirty battery cable battery is weak or cilenoide is going out.
When you open the hood , does the underhood light come on ? Or , if the drivers door is open with the key in the ignition do you hear the warning chime sounding ? If not , it sounds like a poor battery cable connection or a dead battery ( you could have a dead cell in the battery , in which case you can boost the battery to start the car , but if you shut it off it will not restart unless you boost the battery again )
Get a new Battery? or a boost?? if it's standard i guess you could always push start it