As I understand it, if the policy was assigned to the lender then they can, and probably have already, cash/ed it in. You should be able to check whether it was assigned by looking at the terms & conditions in your endowment policy or mortgage terms & conditions.(posted 7221 days ago)Contacting the lender or the insurer will almost certainly provoke them into contacting you again. Though it's highly likely they'll be chasing you again soon anyway, they usually do after 6 years from date of sale. Not as they would have it to give breathing space, but to cut out any possibility of the borrower taking a case to court where the property has been undersold, for example.
In any event if this policy still exists (which I doubt) I think it would be wiser to use it to reach a negotiated settlement (after having put the lender to strict proof, of course).
Mark.