My 2000 Lincoln navigator will not start a change this solenoid the starter is good and the battery is good and the fuses are good

Starter solenoid relay switch ? https://www.youtube.com/watch?v=psqxVvU5Hig

How much weight do you have on the key ring?

Sound Like Transmission Position Sensor ... a sensor determines when you are in Park when stopped...if not, wont start...

Other solution could be Fuse Relay...do you hear buzzing sound coming from fuse box. If so, feel which one is failing and replace. $6 at Autozone....

im a import guy ..im tell u its your battery post tht went b ad they cost 10 dollar ez fixs good luck

could be the starter solenoid or your battery checks out fine on voltage but does not have enough amperage. you can take both to the auto parts store and have both checked out.
after thought make sure you battery contacts(cable connector) are clean dirty corroded contacts cause amperage loss.

Did you check for B+ voltage at the heavier gage wire on the back of the alternator ? When yor turn the key to run , not start , does the charge indicator light ? When the vehicle is running is that charge light lit or off ? There is a fuse that supplies B+ voltage to it . Fuse # 30 located in the central junction box , it's a 30 amp fuse ! Plus one more fuse located in the battery junction block # 11 20amp . With out B+ voltage at these connections on the alternator it will not charge .

faulty ignition switch

Where are you stuck?
Removal & Installation 1. Disconnect the negative battery cable. 2. Raise and safely support the vehicle. 3. Remove the starter terminal cover. 4. Remove the terminal nut and separate the battery starter cable from the starter motor. 5. Disconnect the solenoid (S) terminal connector, if equipped with a starter mounted solenoid. NOTE: To disconnect the hard-shell connector from the solenoid (S) terminal, grasp the plastic shell and pull off; do not pull on the wire. Pull straight off to prevent damage to the connector and (S) terminal. 6. Remove the starter motor retaining bolts. 7. Remove the starter motor from the vehicle. To Install: 8. Place the starter motor in position and install the starter motor retaining bolts. Tighten the bolts to 15-20 ft. lbs. (20-27 Nm). 9. Install the battery starter cable and a terminal nut to the starter motor. Tighten the terminal nuts to 79 inch lbs. (9 Nm). 10. Connect the solenoid (S) terminal connector, if equipped with a starter mounted solenoid. 11. Install the starter solenoid safety cap. If equipped. 12. Lower the vehicle. 13. Connect the negative battery cable. Start the engine several times to check starter motor operation.
Let me know how you make out..

The solenoid is on the starter. There is a fuseable link spliced into the solenoid wiring near the solenois connection

if you dont have any dash lights when you turn the key on then you have blown the MEGA FUSE