Why can't you refund items that were purchased while you were dead?

When you refund you lose the health and mana you heal up in the fountain as a price. When you are dead, you have no health and mana to pay. In addition, when you are alive, most of the time you are in a rush and want to get back to lane asap. When you are dead, you have all the time in the world to select your goods.

it has happened to me that sometimes i cant refund it, but most of the time i can, it must be a bug that makes the game think since you are out of the fountain then you cant refund

If you move when you come back, you can't refund the item that you bought while dead, but otherwise, you should be able to refund it