Conclusion
Anosmia, which is the medical term for loss of the sense of smell, can be temporary or permanent. It can be traced to several causes, including COVID-19, head trauma, and allergies. In most cases, they are temporary and would return after some time.
However, there are some at-home treatments that can help speed up recovery, most common of which is smell training. Over-the-counter and medical treatment can also help. It is best to visit your doctor if the condition is not responding to at-home treatments.
Reference:
[1] https://covid19.who.int/
[2] https://www.healthline.com/nutrition/castor-oil
[3] https://www.webmd.com/balance/ayurvedic-treatments
[4] https://www.sciencedirect.com/topics/neuroscience/vitamin-deficiencies
[5] https://www.nhs.uk/conditions/malnutrition/