Back door lock seized

[Mid]

I have recently moved into a house that has been unoccupied for 12 months. The back door mortice lock appears to have seized completly - when I put the key in it doesn't turn either way.

I have tried plenty of WD40, but still no success.

[carousel88200]

i think you'd be best off taking the lock out and having a look inside, chances are the lock mechanism inside has rusted up and jammed.

[PNC]

Is the door locked shut?
How far does the key turn either way?