What rights do I have to my father’s property under a will?

If my father’s self-acquired property has been transferred to my mother’s name, and she is closer to my sister, I believe that after my father’s death, she wouldn’t want to give me any share. If my father has made a will, do I have any right to any of the properties? I have been alienated from the family and am the only son. This is all due to my mother’s manipulation. Now she is a U.S. citizen, and my sister is married and lives abroad. My father has even made a letter of disownment. Do I have any chance?