My father died and didn''t have a will, he had custody of my son. He had a house, bank account and truck my sister took everything am i entitled to 50%

yes - you are entitled to 50% of your father's estate by way of intestate succession.  If the house, bank account and truck were owned only by your father, and were not jointly owned by your father and sister, then those items become part of the estate and you get 50% of those things.  If your father owned these things jointly with your sister then she is entitled to them as the surviving owner.