ford focus y reg?

I have a y reg focus ghia and have just had a problem with my drivers door lock.I have always used the key to open the driver door,but now it seems not to connect to open.I used the centrol locking on the key ,but it didnt work.I opened the passenger side with the key,and opend driver side by hand.I sat inside and closed the door and used the door lock ,but could not open it from the inside after that.Managed to open it by waggling the key in the lock.Is there a cure