Second Wife and step daughter took it all

My father remarried when he was 78 years old. His second wife had him sell his house and buy a new one with her name on half of the title here in Texas.

Before father passed away, but after he had 2 strokes and the second wife put him into a rest home, the daughter of the second wife, who lives in Tennessee, had Power of Attorney. Unknown to my father, about three months later, from Tennessee and across state borders, she transferred my father's half ownership of the new house to her mother, his second wife. Following his death, the second wife and her daughter left Texas. The daughter is the Executor of the Estate of my father's will, but I have never seen my father's will.

He had a will and both he and the second wife once said that my name is in that will, but it has been four years and seven months since his death, and the will has never been probated. I understand that after four years the law says that legally it is as if he never had a will, so no matter what the will said, I should get half of my father's estate.

My question is: How do I probate his estate to get my fair share of my father's estate?

Any help or direction will help me right this injustice, thank you so much.