Ford ranger won't start

Loosen the nut on the battery terminal ends and remove each cable (take off the negative one first). You can use sand paper or steel wool to scratch the battery posts clean and inside the battery terminal ends. There is a starter solenoid on the inner fender that you can jump to tap the starter. You tap it over by shorting the positive side of the solenoid (large bolt on battery side) to one of the smaller posts. Be very careful, make sure the transmission is in Park or Neutral and the parking brake is set.