You sure it was deer? That's how my pumpkin vines look (cracked in half, lengthwise) But it's from SVB.

You can try burying the main stem with compost and it might send out roots and survive. I have a butternut squash I managed to save by doing this, but only that one. I've lost at least 5-6 squash plants that I tried to save that way but didn't make it in time.

There are deer footprints all around them, so I am assuming it was the deer. They had been doing fantastic up until now, very green lush leaves and lots of pumpkins forming.

Well, I suppose then it would depend on the damage to the plants.. Still might want to throw compost over the main stem, and hope it sends out roots. I'm still a novice so someone might have better advice, but it's all I can think of.

I've been surprised by what plants have lived through in the past, multiple times.. It might just surprise you.

pumpkin vines send out a lot of roots from the leaf nodes, as long as you let them grow on the ground and there is dirt underneath the vines. if so there are probably many additional roots that have formed, so they should be fine.

I've had many plants keep growing and produce even though they've been mostly cut off from the main stem (due to SVB damage)

Well that's reassuring because I'm currently watching mine.. It's been tore up bad by them, but somehow it still has half it's leaves that are green and perky.