Thanks, It appears that Your father has suffered a CVA(Cerebro Vascular accident), It can be a bleed in the brain or an infarct(an area of brain without blood supply). Both the lesions are treatable provided the size of infarction
or bleed is small and there are no associated secondary damage to the brain or lungs. Its very difficult to give you the time he will take to recover as it depends on several factors. please contact a neurologist
at an earliest.