fermenting apple cider

hi! my boyfriend’s family presses apples into cider every year, and we came home with 12 quart jugs of apple cider that we didn’t have fridge or freezer room for. it has been left on our kitchen table for a couple days, and i realized yesterday that its started fermenting. is there any way to save it? i happen to know that it makes a very good hard cider, is it possible to add the correct yeast now and still make hard cider? could i make some into apple cider vinegar? i’m completely unknowledgable about the brewing process and a couple pointers would be unbelievably helpful. i just don’t want to waste all of this lovely cider. thank you for reading!