Turn key and just clicks - 1997 Ford F150 Regular Cab

That's it, that's the definitive answer-it clicks in the tank? The pump is bad, and will need replacing. It should turn on for about 2 seconds to pressurize the fuel line and system with key on-that is the hum you refer to.

If your security light is blinking.Turn key to on position(2 clicks) wait for 10 minutes security light should stop blinking.Turn key to off position. Turn key forward 2 clicks wait for 5 seconds and try to restart the car.

check for lose wire connection off wires on solinoid and battery solinoid is connected on stater motor normally on the side off engine at the back off engine

THAT'S WHAT I THINK IT IS

If it just clicks once when you turn the key it sounds like your battery. If it clicks multiple times when you turn the key, like a ratchiting sound, it is probably your starter.

Sounds like the anti theft system is engaged.

starter

Some of the Ford Keys DO have an antitheft chip in them. so this may very well be your problem... If your other key doesn't have a big plastic Ford scripted head on it, then it's most likely not going to accomodate the antitheft device.
Also the "clicking sound" you mentioned, may be a simple drained battery and it's got enough power to run the lights, but when you turn the motor over it just clicks... Very typiccal forr this to happen as well. Get a jump start and see if that solves the clicking... Best of luck on this..

Do you have memory seats as well? If so follow these steps I am going to refer to the keys as A and B as you have 2 of them
1) Unlock car with key A
2) Turn ignition into ON position with key A and roll down the window
3) Point Key B at IR Sensor and Click twice (perform both clicks under 5 seconds)
4) Turn off ignition and pull Key A out
5) Turn ignition into ON position with Key B
6) Point Key A at IR Sensor and Click once
7) Turn off ignition and Pull Key B out

Key A should be programmed as the Master Seat Program and Key B should be programmed for the Secondary seat program
So when you set your memory seats Key A is for Memory Position 1 and Key B is for memory position 2
if you don't have memory seats then you only have to point the receiver at the sensor and click once. That should just sync the IR Frequency and Codes

your starter is bad.... the two contacts inside the solinoid are worn out only way to fix is replace the unit as a whole bet ya you get click click click then my start.. bet my life on this one been fixin toyotas for 20+ years