Hi. The cellular components of blood (red cell, white cell, platelets) are produced in the bone marrow. If your dad's doctor said that "his body is no longer producing blood", he most likely has something wrong in his bone marrow, which prevents it from producing blood. Various conditions can result in bone marrow injury/ destruction. Cancer (e.g. leukemia or lymphoma) can directly invade and destroy bone marrow cells. Certain chemicals (e.g. benzene), drugs, infection (e.g. hepatitis or Epstein-Barr viruses) or radiation exposure can also damage the marrow, leading to a condition called aplastic anemia. I think a bone marrow biopsy or aspiration is necessary to find out what your father's condition is.