Can you please help

I have just brought a new house and it came with the Thermostat not connected, the wires I have sticking out of the wall are not your usual colors. I have Green, Green-white, Blue, Blue-white and orange (these wires were stripped). Then I have Orange-white, Brown, Brown-white.

That sounds like they used Cat 5 type wiring(Normally used for Computers)also called UTP. Light gauge wire, more likely to fail
I would run new Thermostat wiring, Red, White, blue, green, yellow. In brown coating.
Should be short run.
You will have to Open Air Handler and look at where wires are connected,Take Notes
Color scheme was most likely made up by one who connected unit. Not Normal
At thermostat:
Red is common
White is heat
Green is fan
Yellow or blue cool.

Sounds like telephone wire and not thermostat wire...