Just to summarize the responses for future people searching this topic, all the above recommendations are valid and fixing a non-working or non-igniting furnace requires some patience and troubleshooting. Some of the symptoms might be similar to other people but the cause of the problem and subsequent fix can be different.
In my case with the bad gas valve, they get sticky with old age. It's basically an electro-mechanical piece composed of a electrical solenoid that moves a shaft to open/close a gas valve. Mine would not work when cold and then would sometimes work and sometimes not. I could hear the furnace sparking and trying to ignite the gas and but my initial diagnosis was that the house battery was weak in cold weather. However my testing of the battery did not confirm that condition. The electrical connections seemed to be good. Finally my friend suggested replacing the gas valve. For the cost of doing so it was worth my time versus having a shop check it out although replacing the valve was a pain because of the tight clearances to get to loosen the connecting pipes.
