How can I go about claiming my funds?

My grandfather created a will and trust before he ped away which was in september 05. He ped away in october 05, and he didn't want to leave the trust to my mother, but he had no choice too since I was a minor at the time. He left the estate to my mother and myself (minor beneficiary) and he left us both inheritance checks, which had $15,000 but it was divided in to 2 for both my mom and myself, but she forged my name on my inheritance checks to pay for her own expense and left me with about $500. I turned 18 on may 07, and she put the house up for sale in nov 07, now it's sold and we are in the moving process. Since I am 18, aren't I entitled to half of the proceeds? My mom doesn't really care about me and could careless if I'm homeless. How can I go about claiming my funds?