How do you check to see if the gas spigot on a furnace is break open? Yesterday heater go out. At first igniter was fine later went out...

Yesterday heater go out. At first igniter was fine later went out and nil happened, thought might be igniter. Replaced & still zilch at all. Turned out when blew circuit from adjectives the electric heaters turned on forgot to turn on the breaker for the furnace. Did that & still nothing. A responder said to check gas valve- I looked at it and enjoy the operations encyclopaedia but don't know what to do to it. Also, was told to reset switches-- are they the really tiny, just pushable things? According to the manual I'm contained by the right spot but they don't press that much.
How do I draw from my furnace to...
Answers:    Gas valves generally have a button or raised piece of brass for turning them on and bad. The direction of the handle will detail you if it is on or off. If it go across the pipe, it's off. If going like peas in a pod direction as the pipe exiting it, it's on. Those are micro-switches and they don't move much.