[billybek]

Sounds like you may have a problem with one of the safeties.
First, have a look at your thermostat and if it has switches on it for "Cool/Auto/Heat" make sure that switch is set to Auto or Heat.
Second, what make of furnace? Some have their terminal boards numbered differently.
Third, do you have an electrical meter?
If you do, set it for A/C Volts and when the furnace is NOT calling for heat (turn the T'stat down to a low setting), check for voltage between the R terminal (24 VAC) and W1 (first stage heat).
If there is voltage potential of 24 VAC shown on your meter, try to jumper these two terminals together and see if the furnace starts.
If it starts, it is the thermostat.
If there is no voltage potential between R and W1, then you may have a safety open.
usually there is an over temperature switch with a manual reset button in or around the closed combustion area of the burners or at the exit of burner section on a mid efficient furnace.
Try that first and see what happens.
Oh ya, and RWest is correct in that most of the printed circuit control boards will flash out a failure code. Look at the back of one of the removable panels or the owners manual for what the different flash codes mean.