I'm sorry you are hurting. Loss is never easy and when there are insufficiently answered questions, it makes everything more difficult.

I don't know what you can do to win back another's affection. I personally have not been successful at doing that. What I have been successful at is being the best me I can be. I struggle sometimes, but I focus on being me and finding what brings me happiness. Sometimes it's a small thing that makes me happy like hearing people laugh. Sometimes it's listening to rain after 2 months of drought. Everyday I am grateful to have a chance to find happiness. The only thing I know for sure, my happiness is not someone else's responsibility and it is not in the past.

My advice is to find what makes you feel happiness and live in now. The future isn't written and you deserve to be happy. I wish you all the best.