Do you know what the will said? Have you traced where the solicitors files went by contacting the Law Society? Who would benefit if the estate proceeded without the will, ie, do you have brothers and sisters?
Can you find out what happened as that will be important if I am to help you with this
Normally if you are attorney you would not be sued personally for care home fees. It is the person in care or their estate which is responsible. You should defend the action on that basis unless they have any evidence to show that you agreed to be personally liable. What have they said about that in the court action?