The MicroLogix 1200 does not have battery backed RAM, so you'd have to clear the memory via your programming software. If you have a communication issue, then you may reset channel 0 to factory default parameters by pressing and holding the "Communications Toggle" pushbutton for 1 Second.
EDIT: I didn't realize that you had made multiple top posts on this same issue, or I would not have replied. That represents poor forum etiquette, commonly called "page pushing". You are forcing other forum member's threads off of the front page by engaging in this behavior. It would be preferable to simply post a reply in your original thread to bump it back to the front page if you haven't gotten a response lately and still do not have your problem resolved.
Best Regards,
BB7