Can my step-mother sell property of my deceased father

I am 20 years old and after death of my father my step-mother sold some of his properties without telling me. She has one son and a daughter from the wedlock. I am not aware about the number of properties in his name neither I have documents related to those properties. What can I do if she has already sold some of the properties? Is there any way that I can get documents of sold and unsold properties without involving her? She also possesses papers of properties which are exclusively in my name how can I get duplicate copies of those?