Ford Focus Central Locking?

Hi i have a 2002 focus and when i turn the key in drivers door all doors unlock except the drivers door (a bit of a pain climbing in from passenger side), not had a new key or anything to caurse this problem, it's just started this morning although yesterday as i was unlocking the car the drivers door lock felt a bit spongy (for want of a better word) but this is the only way i can describe how the lock felt. Please can anyone help