Why Would Facial Hair Stop Growing on a Man?

Facial hair loss in males in multiple spots is termed allopecia barbae and is very similar to allopecia areata. This is an autoimmune process were your body fights the hair follicles until they no longer reproduce hair. There are some topical treatments that are useful during the early stages. Hair transplantation can be used to restore hair to the brows, sideburns, beard, and mustache.

In general, men with bald spots on the neck that regrow with white hair are likely to have alopecia barbae but be sure to see a dermatologist for confirmation and to discuss treatment.Alopecia barbae is one type of alopecia areata. Alopecia areata affects 2% of the world's population so it is common. It is a type of "autoimmune disease"Hair transplants are not generally an option for individuals with alopecia areata or alopecia barbae so be sure to see a dermatologist who specializes in medical treatment. 

What you are describing is a well known disorder when your body's own immune system is causing damage to your hair growth and you should see a dermatologist.