hello i was wondering when my pareants were married my father assign me my

hello i was wondering when my pareants were married my father assign me my sister and brother the house well when they divorce my mother was left alone to care for the house she couldnt handle taking care the house so an inspecter told her she couldnt live their any more she left the house i guess the government or whoever broke down the house n after several years someone built a house on our property my mother said my dad was in several car accidents and he owe money that i think some how went on the house and he had to pay which he didnt so when someone built their house on our property i was wondering how was that person able to do that mother said that someone came to her and asked her to sign over the house and she refuse what are my chances on getting back our property sense my father gave over the house to me and what can i do who do i speak to do i need a lawyer? please i really want our property back and what about the house they built on their will i be able to get the house or just the property please get back im confuse