I have a 6 wire thermostat

X - blue
W2 - white
R - red
g - green
o - orange
y - yellow

The thermostat is an old LR69071

Now my heat pump does not wirk at all after trying to install a white-rodgers 1F83-277

Sounds like crossed up wiring somewhere did instructions come with the w-r?

sounds like crossed up wiring somewhere did instructions come with the w-r?

What I am looking for is what the X on the old thermostat is for

Is probably the common wire,you said it was blue,go to the furnace trace the tstat wires where they hook to furnace what is the blue wire going to?

The common isn`t necessary it sends 24 volts to the tsat so you can run without batteries in most cases,, but check it out

Based on your description, "X" is the low voltage common (as wmproop stated). If the new thermostat has a "C" terminal it would connect there. Be sure "Rc" and "Rh" are jumpered together (if both are present).