When i try to start my 2003 expedition, it wont turn over. it just makes a clicking noise. not even a grind, just a clicking sound

Do you know how to test automotive electrical circuits ? Using a volt meter an wiring diagram to locate problems ?
Free wiring diagrams here http://www.bbbind.com/free_tsb.html Enter vehicle info. year ,make , model and engine size . Under system click on engine , under subsystem click starting . Click the search button then the blue link . The buzzing sound you hear may be the starter relay , do you know what a relay is ? Behind the right side kick panel , this is where the front passengers right foot would be next to . Pull the plastic cover and behind is the central junction box. You can check for B+ voltage where the relay plugs in .
VEHICLE RELAYS Operation Diagnosis

Electric Testing Techniques You Need to Know

Ford F150 5 4 No Start No Crank No Communications Codes U1900 U2023

If you can hear a click (quite loud) from the engine compartment, but the starter won't crank, this also could be caused by discharged battery-----------------------------------------------------------------------------
vas 5054a

Turn your key all the way back towards you in the battery only postion. Then press and hold the red alarm flashing button til you hear the beeping noise it makes. This will disable your alarm and your car will start.

If its a grinding noise, it could be the starter or the flywheel gear.

Possible defective starter but most likely Flywheel.

I would check the wheel bearings first.

is it a sought of loud clicking crunching noise, if so its your CV joints have broken they don't seem to cause much of a problem apart from the noise but eventually they wont work at all and affect your handling and they are a ***** to replace

You battery may be going out or mostly likely that your starter is going out and wont start your car and can make a clicking noise when you start it.

sounds like a wheel bearing

It's the temp blend door actuator.