Primarily, to smell anything, the odour molecules should be able to reach the uppermost reaches of your nose where the olfactory mucosa is found. So, if you have any nasal septal deformity or sinonasal polyps, they could obstruct the smell pathway leading to blocked smell sensation. So, a detailed CT scan of your nose and paranasal sinuses will reveal to your ENT Surgeon whether the smell sensation is impaired due to obstructive causes. This can easily treated by medicàtion or/and surgery.