Hi.. You may need evaluation to know the cause for the problem. Only when a proper cause is found the treatment can be directed.. It could be a sensitive problem hence it is better to get checked..
Puberphonia is the persistence of adolescent voice in an adult especially in the absence of any organic cause(such as hypogonadism which may require hormone therapy).
Treatment will depend on your age and may include Speech Therapy, Laryngeal manipulation techniques and/or laryngeal surgery or Type III Phonosurgery (Thyroplasty).