How to find out if I was left anything in a will

Hi. Not sure if this is posted in the correct place

My grandad wants to find out if his brother left him anything in his will. He had no children and he is sure he is entitled to something, he knows he wrote a will as his brother told him but never mentioned what he had left and to who. Their sister is dealing with all the finances and selling the property and she is more able bodied but she will not speak to my grandad about any matters regarding a will so how can we find out if he has indeed been left anything?

Thank you