I have noticed that my beard has become thick and hair on head thin. can i reverse it ?

Partially: You're a naturally hirsute man and will tend to early balding. Many people think this looks good. You can shave/buzz your head and grow some facial hair, or you can use one of the topical or oral medicines that slow masculine hair loss, or if you wish you can visit a physician who specializes in hair restoration for a procedure. It's your decision, made with a partner if you have one. Best wishes.