how to disable the anti theft alarm ? on 1996 Volkswagen Cabrio

Recently replaced a fuel filter on my car, and when i replugged the battery the anti theft alarm re armed itself, stopping me from trying to restart the engine( won't crank at all) and i can't find the stupid sensor that's stopping it from turning off. Any ideas?

Asked by for the 1996 Volkswagen Cabrio
You can try to use the key to lock and unlock all the doors including the trunk, then try to start. (2) put key in ignition and turn to the on position, let set like that for ten minutes then off then try to start. (3) If none of those work you will need to have the theft system reset with a scan tool.
We just replaced the starter and to my surprise the vehicle has an alarm. I only have one key to it. How do I by pass the alarm?