There are multiple causes for anosmia such as head injury, nasal polyps, allergic rhinitis, idiopathic, post viral etc. Most common cause is post viral which occurs because of viral infection. If your CT is normal then chances of post viral anosmia are high. You can try a course of steroid nasal sprays which sometimes can be beneficial
Next Steps
Consult nearby ENT specialist for confirmation of diagnosis and appropriate treatment if required