Their dA ( https://sapphirelullaby.deviantart.com/ ) seems abandoned and tumblr account under sapphirelullaby seems to be in use of some advertising bot.
I also tried googling their PP address but found nothing useful.
Does anyone know if this artist is still active anywhere where I could contact them? It's waaaay beyond PayPal chargeback by now and that's my fault, but I had commissioned this artist in the past with no problems :(