How can I fix my ignition of my 2004 opel corsa 5-door hatch back?

When I remove my key from the ignition, my doors are surpose to unlock, it does not, when the is in the ignition and the door is opened a warning sound is made as soon as the key is removed the sound is surpose stop but it does not and my remote central locking does not work...... I think it is to do with the ignition not sensing that the key is removed, how can I fix this?