The ignition is a system made up of lots of parts. You don't replace the whole system. As for a "no-start", that can mean a dozen different things. Does the engine crank at the normal speed? Do you just hear a single click each time you turn the ignition switch to "crank"? Do you hear a steady buzzing or ratcheting sound? A single rather loud clunk? What happens to the brightness of the interior or head lights? Do they start out bright, then go out or dim when you crank the engine?
Have you measured the battery voltage? It should be 12.6 volts. If it's around 12.2 volts, it's good but discharged. At closer to 11 volts it has a shorted cell and must be replaced. There's no way we have of knowing if you need a new battery. That's what mechanics are for. You can diagnose it yourself but we have to know where to start.