Changed ignition switch now my car will not start

Just need to clarify some things. You lost your keys so you changed the ignition switch so that if someone found the key, they could not steal it? If this is the case, you went to a little too much trouble. You can have all the keys erased and then program new keys. This will disable all existing keys and program new ones so that the new ones are the only that will start the vehicle.

Now that you have new keys cut to the new ignition, did you program them?

If not, and you don't have any that will work then you need a scan tool to program them to the vehicle and then they should work.