You need to get an experienced person to determine the most likely
cause of the crack. From that you will know whether it is an insurance
issue, or due to some other parties actions - or if it's down to you.

Are we talking about a crack you can fit your hand in? Or just a coin
on edge? Is your house a new build? Is it on flat ground? Are there
neighbouring properties having similar problems? Are there trees too
close to your house? Could there be a leaking drain underground?

There's a lot of possible causes, many of which aren't likely to be
covered by insurance.