Loss of smell sensation is usually caused by acute sinusitis, rhinitis etc.CNS causes are brain tumour,aneurysm,hormonal disturbances,
diabetes,multiple sclerosis,
zinc deficiency, malnutrition etc.Loss of taste sensation can be due to nasal infections,flu,common cold, dryness of mouth, medications like antithyroid medications,rifampicin,gingivitis,vitamin B12 or zinc deficiency. You should consult a primary care physician.