After replacing the ignition, the security light is flashing?

If you still have the old ignition cylinder, call a locksmith and have them cut you 2 new keys to fit that cylinder and then they can use a programming tool to erase the old keys from the PATS and program in the new keys. Then your new keys will also fit the other locks on the car. With no good keys you need a programming tool or a scan tool to be able to program in replacements using the "lost all keys" function in the tool. There is no other way to program in keys. There is also a minimum of 2 keys required and with 2 good keys you can add more.