Hi @phil_a_show ,
There are two “common” methods of connecting a TRRS jack
(click on image to enlarge for better viewing)
You may be able to work out which wire goes where by using the Ohmmeter or a 1.5V AA battery and some test leads.
I would start with connecting the Ohmmeter across the Green and Copper wires and see if there is a reading or connecting the battery on and off across the same wires and listen for the clicks in the left earphone.
If there is then at least you now know the wires for the “tip” (green) and possibly the “R2” or “S” (copper)
Next try the same with the Blue wire and the same copper wire and check if there is a reading or a “click” in the right headphone.
If there is then at least you now know the wires for the “R1” (blue) and possibly the “R2” or “S” (copper)
That just leaves the red wire and the red/earth wire which should be for the microphone.
This is where it becomes trial and error whether you connect the red to R2 and the Red/Copper to S along with the other copper wire or connect the red to S and the red/copper along with the other copper to R2.
If you get the headphones to work first before working out how the microphone connects at least you’ll know which connector ring is the Common (or Earth) connector. Then it is just a matter of determining which is the microphone wire (the red or the red/copper - is it a shielded wire perhaps?) and which is its’ earth return wire.