You are only 21 yrs, hope u r not married yet. In that case this erection issue is not important.
Regarding masturbation practice u should abstain from such practices. As it is the best part of our structural component.
If u r married and suffer from erection issue at this age, u need to consult across the table with Doctor.
Self medication is injurious to health devoid of any system like Ayurved, Homoeopathy or Allopathy.
Next Steps
concentrate on constructive activity.