My older freestanding furance will not burn. Pilot is running and thermostate is working properly. Thermocoupling just replaced. Help

Explain freestanding furnace.
Exact model number?
Name brand?

Sorry but my crystal ball is broken at this time and I can no longer see that information from a distance.

Is this the Freestanding 5000 or the Freestanding Ultra? We need you to be more specific...