Hello and welcome to Just answer,
Power is supplied to the headlamp switch through the PARK fuse in the Instrument panel fuse block, then the headlamp switch directs the power to the park lamps and the instrument panel lamps. In order for one thing to take out both park and Inst. lamps the problem would have to be between the fuse and the headlamp switch.
The orange wire in cavity "H" of the headlamp switch connector is the wire from the PARK fuse. There could be a break in the wire or a problem with the terminals on the ends. The brown wire in cavity "S" leads to the park lamps and the dark green wire in cavity "E" leads to the inst. panel lamps.
If you have a voltmeter or test light to check voltage here and across the fuse this could help narrow the open in the circuit down. Let me know where you do and don't have voltage and we can go further if needed.
Below is a schematic of the system
The headlights recieve their power from a different source than the parklamps.
Does the orange wire have power to the headlamp switch?
How have you verified power at the orange wire?
If the orange wire has voltage and you can bypass the switch by connecting the orange to the brown and the park lamps work, then the problem is either the switch or the terminals on the end of the wire not making good contact with the switch terminals.
Even if there is no discoloration or pitting the terminal needs to be tight on the head lamp switch pin.
Since you have tried 2 switches, then the problem has to be with the terminals.