First thing you can do is voice rest, it is the only solution for your problem. You can make conversation with a very low or whistle voice or with indications or in writing mostly in boards while taking classes, Or you can present in PPT where you don't have to speak much. Next thing you can go to an ENT specialist for a Laryngoscopy to know the status of your vocal cords.
Next Steps
also you have to take plenty of water, steam inhalation at least 2-3 times a day.