Compromise in sense of smell can be conductive due to some local issue in the nose like obstruction poylp which doesn’t allow the smell to reach the sensory epithelium of smell in the roof of the nose or sensorineural due to problem in nerve, u need a detailed evaluation with nasal endoscopy and ct scan

One year means a long time. Smell training is a mainstay of treatment. In smell training, you need to smell a series of four strong odors that can be found in one’s home, or in the form of essential oils. Each scent is gently sniffed for 20 seconds. This process is repeated three times daily for 6 weeks. Long-term commitment is typically required to see improvement. Smell training may be most effective if you work on the same four odors each day, rather than alternating. It is recommended trying these scents: ground coffee rose citrus eucalyptus vanilla clove mint