Also make sure that your car's CNG kit is turned on (if it has one). My car refused to start the other day and I figured out that it was a loosely connected CNG switch wire due to which the kit wasn't starting. Even though I do not use CNG anymore but still the kit is required for petrol delivery to the engine if it is installed. So watch out for that as well. If you turn the ignition on and engine check light is not blinking, everything looks normal and car is not starting, see if the cng kit button light is on or not.