dadoc

I have a patrol line car alarm fitted and when i had to change the car battery last year the alarm function got reversed ie it would arm when opening the door and disarm when locking the door. i have a key that i can put into the alarm and has two positions.I turned the alarm off at the time but now it wont work at all, if I put the key in the alarm and turn it on and then turn on the ignition the led will light in the car.Does any one know how to reprogramme the alarm?