There is no cure however, you should keep the extremities warm in cold weather and, if the problem is in the hands rather then the feet, try not to use vibrating equipment etc. which can aggravate the problem ('white finger').
Reynauds Phenomena or Syndrome? Phenomena is where the fingers go blue/green/white and hurt when they warm up. Syndrome is more serious and can indicate heart probs. for white fingers your doctor may prescribe the spray used for angina which stimulates circulation, there is no cure but it should get better as you get older it's worse in women between 11 and 30