There are a number of things that could be causing your starting issue. Need a bit more information:
Are you getting that ticking/clicking sound when you first tried to start it? That might indicate a weak battery, poor battery connections, or bad starter contacts.
Also possible, given that it seems to start right away after rowing through the gear shift, that your neutral safety switch could be faulty. That is part of a circuit that makes it permissible to start the car, don't want to start the car in gear - only park and neutral. Possible that it doesn't know exactly where the shift position is (bad electrical connection, lever arm on the side is damaged or not connected, etc.) - so it may not know what gear it is in - not allowing the starter to turn over.