if you carefully pull on the liner it will fold down.
You have to replace the entire assembly.
The headlight assembly is only held on by a couple screws and can be replaced in a couple minutes.
It's easier and more economical to replace the axle assembly with a rebuilt one.
The converter assembly is a bolt on part, or you can cut out and weld in generic units to replace the existing ones.
Because your switch is bad, replace the light assembly
Remove the wing nuts from inside the trunk, the assembly will pop out.
If you're talking about the headlight, the "lens cover" is not a separate part, you need to replace the whole headlight assembly.
Unless you have a California model, the converter assembly sells in the aftermarket for about $300.
The front wheel bearings must be pressed into and out of the spindle/hub assembly. You will need to take the spindle assembly to an automotive machine shop to have this done.
Unplug the sensor and unscrew it from the exhaust pipe. You'll probably need a special socket to do it without damaging the wires.
You either bolt on a new assembly, or cut the old ones out and weld generic units in place.
replace keypad Mercury Marquis?