Just replaced the key ignition switch and the car will turn over but will not start.
The chip in your new key hasn’t been programmed to your car.
You’ll need a mobile locksmith that has the capability to program it to your car to come to you, or have your car towed to a locksmith or the dealer.
If you still have your old key, you might try holding the head of it next the new key while trying to start.
EDIT:
You could also take the new cylinder to a locksmith and have it re-keyed to your old key.