My fan pull chain will not turn off the light. The fan turns on and off with no problem. There only white and black wires. 4 light bulbs.

Have to clear up a few questions before I can help you. Are there 2 pull chains, one for the light and one for the fan? Does one make a sharper click when you pull it?

You probably have a bad switch. Turn off the fan and light, drop the light and remove the switch, usually 2 small screws. Take the switch to an electrical supply house, HD or Lowe's too and match the switch.