More than likely the battery is discharged. It can also be a defective starter. Fully charge the battery and see what you have.
Are you positive the battery is dead? Have you tried to jump start it? That clicking could be the starter relay.
check your battery then the connections if it still wont start try changing the starter solenoid if possible
dead battery or bad starter (with the clicking, I'm 95% sure its the battery)
Does the engine turn over and then make the clicking noise while trying to start, or does it not do anything but make the clicking noise when you turn the key. If its not turning over at all then it might be a battery problem, Try cleaning the battery terminals, and/or charge the battery, Could also be the starter solenoid, but start with the battery first.
Dead battery or dirty/loose battery connection.
charge the battery, change the battery, use the back up start either a pull start or kick start.
Low Battery
Maybe flat battery?
Replace battery cable.
If there is clicking, that means the car has power from the battery so the altenator and the battery are good. I would suggest that the starter is gone bad. It will eventually grind away to where there is no clicking.
Low battery voltage .?
Clicking usually is a sign of a bad battery or starter