Mistaken removal from will

I think my son has been underhandedly taken out of his great grandmother's will. For the last 9 years of her life I was told by his greatgrandmother that my son would be taken care of when she died. She opened a trust in his name. She passed two years ago this Novemeber and I have still have not heard from any family members or lawyers. How can I find a copy of the will she had?