He sounds very much like my friend who had the stroke. He was like that for the first few weeks. If you keep asking him questions and give him a few hints now and then he will improve. If he ever had creative interests Like drawing getting him some pencils and a large pad will help. Even if it’s just making marks on a page. It gets hum to manipulate something. Ask him what food he likes. I got some pre-cut apple segments and shared then with my pal and it was like he had never eaten apple before. The look of surprise and delight. I hope your dad recovers well.