5 years ago I fractured my talus bone in 3 places and when I'm sat down my toes go numb and my ankle starts to hurt is this normal?

No. No, i would not say it is normal and there are multiple potential causes. Some talus fractures heal uneventfully, others have serious long term sequelae. Tarsal tunnel syndrome is just one condition that can cause similar symptoms and may be more common in someone who has had such a severe injury as you are describing. Thank you for your question.