I shut off furnace last spring by shutting off gas and pulling breaker. Turn the breaker back on and the blower runs with the thermo turned to off. I've tried to fire up furnace anyhow but it won't start. Only way to shut blower off is by turning off breaker. Was working fine the last time I had it on.

Far too often, things just done' run right after setting unused for a while. How old is it? Does it have a pilot light? Does the gas come on and then go off before long with or without igniting?

The blower could be a separate problem. Is it set on the auto position if the thermostat has an auto/on position for the fan? If so, the relay for the fan could be stuck.