Hot water heater doesn't work 2 years old

Question

4 days ago had no hot water. turned waterheater off and then back on.burner inginited and turned off after aprox.1 min. after 3rd time it stayed lit and heated water.worked fine up to now.turned switch off and turned backed on. fan comes on,you can hear igninter come on but no ignition.tried couple of times . no luck . water heater is a ge power vent
propane heater.