If it is brandless meaning cheap, it is more practical to buy another one? Put this way tripods are not everyday use products in mass use like water taps,toilet accessories where spares are available even from supermarkets.If you are dead set on repairing this tripod then you need to have some diy
technical knowlege ,this is mechanical engineering territory.Is it made of metal,what type..steel or brass or aluminium? How is it attached..srewthread or pressure fit? What size? Then you go to a hardware shop not those neighbourhood ones but industrial type where they sell metal bars and rods.They will probably sell by the foot or meter.If it is screwthread then you have extra headache as you need to cut the screwthread so buying a stanard screw bolt of suitable length that has part of shaft threaded and screwthread dimension and cut or sand down the taper.In this case it would be faster to just do like a four or three sided pyramid shape.For screws and metal rods go to St. Georges road or Kelantan lane shops. Or go to a machine shop and custom order/make.