Subscription refund without digital receipts provided

I found out I was getting changed for a subscription for YouTube music that i did not authorize, I gave my device to my brother when he damaged his own. long story short I didn’t approve that purchase nor do i have the app installed. I’m happy I checked my account or I would not have been aware of my money being taken without my consent. How DO I process this refund without the receiptsI want to issue a refund on the site but it’s showing me that there’s no receipt so I can’t process a refund.