How can I get into my car?

How can I get into my car when my central locking system isn't responding to my key fob and the key doesn't seem
To work the door lock on my golf 1.9tdi 2002 model. My car wouldn't lock at first then it locked but alarm was going off then alarm stopped now it won't unlock the light on the key fob works but the light on immobiliser in the car isn't flashing now help I can't get into my car