Try turning it off at the thermostat; wait a minute and try again.
If there was air in the line, the furnace will try to light 3 times; then SHUT DOWN. It will not try again until power is removed (by turning the thermostat off of pulling the fuse in the power center).
Did the blower come one and did you feel a strong current of air while it was trying to light?
Did you hear the burner try to light?
Did you smell gas at the furnace exhaust port outside?
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW