Driver side door lock

I have a 2000 VW Golf GL. I do not have the alarm pad key I have to put the key in the driver side door and turn it to unlock and lock/set alarm on the doors. Today I went to unlock my car and it makes a funny sound like it is trying to unlock but nothing happens. If I twist the key 2x which is how I unlock the passanger door the passanger door will unlock just fine. Any clue on what might be causing the driver side door not to unlock?
Thanks for any ideas!

need a new driver door latch