Hi
Welcome to the MedHelp forum!
Your father probably has concussion. A concussion can last for weeks after the head injury. The symptoms too vary from person to person. Headache, confusion, memory loss, dizziness, nausea vomiting, slurred speech and fatigue are common. Delayed symptoms include depression, irritability, sleep disturbances, seizures, loss of smell etc. Injury to olfactory and lingual nerves of smell and taste could be a cause or it could be that nerves are in shock. Once swelling and contusion following the fall will subside some taste and smell may return. However, when this will happen is difficult to say. Your father should be shown to a neurologist once. Take care!
I have smell disorder after a mild traumatic brain injury 1 year 3 months ago and still suffering. It may be permanent. Complete loss has been called anosmia. What I am suffering from is everything smells and tastes different what it is not and many times obnoxious. I don't even know the medical term for it.
Unfortunately no one can predict what will be the outcome. Just hope and keep praying. If it happened recently then doctors may say give it about 6 months to 1 year and may come back.
Good luck.