Can avoiding masturbation permanently,effect my body in any harmful way?if yes,how least often should i masturbate to remain in mental n phy. health?

Doesn't matter: It absolutely doesn't matter how often a person masturbates as long he or she is living a normal happy life... and the masturbation is not interfering with one's normal daily activities. If that is not the case, and a person is masturbating too little, or too much, and it's becoming one of life's stresses, then he can take a trip to the doctor's office to evaluate the whole picture (big picture).