Key not working.

Hello guys, I'm having an issue with my key. I have a 2005 3.0 td6. The central locking all works fine but, I cannot use the key to open the door manually. The key goes in the door but won't move. Any ideas?. Also the alarm light doesn't come on, ever. When I get out of the car, lock it, no flashing light. I can lock the car with the remote, leave a door open, no alarm. Again, any ideas?. Many thanks, Andy