How change heat type to gas?

[MarkG1]

On set up my nest 3rg gen thinks I have a heat pump.  The furnace fan turns on but the The furnace does not heat. The thermostat equipment settings will not let me change to gas furnace. Do I need to factory reset and start over?

[Patrick_Caezza]

@MarkG1 

Post a picture of the original thermostat's wiring here.

[MarkG1]

 

[MarkG1]

Have resolved the issue. Original installers connected an  excess (6th) wire to the Honeywell connecting plate - to the o/b terminal. This wire was not connected to anything in the air handler. When I connected to the nest, forced the nest to think I had a heat pump. Disconnected from the nest and now was able to tell the Nest I have gas heat. Furnace lit right off and we have heat.