What size bolt/screw for sliding door handle

Hi what size screw do I need for the sliding door handle the old one is threaded and rusted into the handle so bought new handle thanks

 

M5x15 fillister head (part number N0141313) – if you mean the inner handle on a late bay.

 

I think the only one that could get rusted into the handle would be early style. I have a hunch it's M4. Perhaps the OP can clarify.