I recently lost my younger sister to sudden death wasn’t ill just was found dead
Welcome to the Community. I am sorry to hear of the loss of your sister.
There is an organisation called Sudden that provides support after a sudden death. The website has useful resources and information that will be of support to you.
Sue Ryder has a Grief Guide that will help you understand and cope with your bereavement and grief.
Please continue to reach out here. You are not alone.