Hello there! I just want to say that its okay not to feel motivated. I recently got back into writing and it took me over a year cause I burnt myself out writing almost everyday. But I'm not going to say try writing a chapter on a book you already have. But I do think trying to write about things you are interested at the moment. Maybe even writing one shots.
But I hope you do go back into writing it helps with a lot of things and helps you build up your skills.
*bows down* I hope you try writing soon and not just giving up completely! You can do this!