2000 Vauxhall Corsa Central locking not working

Hi,

My battery on my car has been flat for the last few weeks and i have just recharged it today. Everything is working fine apart from the cental locking doors won't lock.

I can put the key in the lock but when i try and turn it, it is just really stiff and won't move. I can't lock it from the inside either, it's just the same.

Have you got any idea as to what it could be?

Thanks...