I replaced my thermostat with a Honeywell rth2300. The ac was working and heat was not. Now nothing seems to turn on. I have the following wires coming out the wall. Red, yellow, white, black, blue, orange, green. On the Honeywell wall plate I have b, o, g, y,w, not used, r, and rc. Please help me wire this correctly. Thank you.

To what terminals are each of the wires connected at the air handler or furnace?

Yes, the color of the wires means less than the labeled screws they are connected to. Open the panel on the furnace and write dow the single letter label on each screw to see if the wirecolor even matches the screw color, frequently they do not. This is from the 2300 manual "Does not work with heat pump systems with back-up heat, multi-stage heating/cooling systems and electric baseboard heat (120-240V) " does any of this apply to your use, this stat doesn't work with every furnace