It is inflammation of the larynx (voice box). It is mainly caused by
virus and treatment depends on type of
virus affected. Even serological tests will help to identify the responsible pathogens. It can be treated with appropriate anti viral.
But drinking lot of fluids, sucking lozenges, gargle with salt water, breathing moist air to soothe sore throat, refraining from taking decongestants (because they dry your throat), resting your larynx will help you.