Central door lock

[Glynp]

Hi all, little problem
Passenger front door locks under central locking, but will not unlock, does unlock from the door handle inside, ive got a second hand part from a breakers coming next week, ive looked at the Haynes manual, and its not really much help, im sure ive seen some photos on here, but cant find them now.
And any help with getting the door card off, would be a great help too.
Any help would be great.
Glyn