Check the battery cables. If there is no corrosion and you have good connections, then the starter solenoid/relay may be at fault.
solenoid or relay switch
It clicks?What are you talking about clicking? you turn the key to start the car and all it will do is click,click! or when you try to start it it will spin over and then stop and click.! All I can think of if your car battery isn't good enough to start the car and you will get a click or you have a bad starter and it will only click. need more info
if it does not turn over and no clicking noise but headlights on, check start fuse and relay if it doesnt turn over and clicks probable starter solenoid
Bad battery, starting motor or both.
clean the battery terminals with baking soda and water. them jump it
Low voltage. Clicking is the starter solenoid. Low battery on the good car, bad cables or a bad connection. If they are all good, then the solenoid may be bad.
your battery is flat you need to get your battery and alternator checked a lot of parts stores and garages will check them for free
Get a jump start from somebody else, and then figure out what it was you left turned on or plugged in to drain your battery. If it happens again, replace the battery. By the way, this is why you should belong to AAA or another road-service club.
It could be a dead battery.
Could be, the engine is seized, the starter is bad, dirty or loose battery connections, battery in vehicle being jumped is stone dead.
you need a new batt.
How do you know that it is your car?