My keys broke in my ignition will it have to be reprogrammed?

Contact a couple locksmiths in your area. Some do key programming, some don't. The larger companies will help. Explain your situation to them, before they come out. They might be able to get the broken key out and cut and program a new key for you without replacing the ignition switch. Mind you, if the mechanic cut a wire, I would be prepared to splice it back together before or when the locksmith comes out to repair.

I have a 07 cobalt half key is in switch and other half I lost I was using the half key to stick in the switch and start it but I lost the other half what do I gotta do

I had this happen once all i did was slowly and gingerly back it out side to side with picks and a bobby pin.