You should check the battery if it is good. Try checking to see if the power is getting to the starter when you push the button if not it might be a falty relay .If power is getting to the starter (12 volt . If less check power going into your relay ) starter may need to be replaced or repared.
Check your battery first, its terminal connection and connection leading to the starter.
It could be the battery. If not try tapping the starter with a hammer. Not hard enough to crack the housing but hard enough that it might unstick the starter from the flywheel. If this works you might want to change the starter. If not it would have to be the solenoid.
Could be the starter or ignition switch...does the car crank/turn over when you turn the key? If you just turn the key and it 'clicks' it might be the ignition switch. I've had this problem before, and it ended up being the alternator. HOpe this helps!
Could be the Starter or the Transmission
Could be bad glow plugs.
If the battery is bad, you may only hear clicks. It could be the starter, but I would check the charge on the battery first.
If your 2000 Mercury Sable clicks once when you turn the key but doesn't start, it may indicate a problem with the battery, starter, or connections. First, check the battery voltage and connections for corrosion or looseness. If the battery is fine, the issue could be the starter motor or a faulty ignition switch. It's advisable to have a mechanic diagnose the problem to accurately identify the cause.
This sounds like your battery.
could be the master fuse under the hood. is there any electrical?
your battery is flat Could be that your starter is dead. The clicking is the starter solenoid. That's a good thing that it is at least clicking. Replace the starter.
start with checking the battery, next check the solenoid,next check the starter motor.then check ignition switch
starter, solonoid, ignition, battery. if it clicks when you turn the key then the battery is really dead or its the starter the battery could still be jumped if its the battery.