How to repair a twisted Presta valve?
As noted in this old question there exist Presta tubes from which the valve core can be removed; in this case it might be possible to replace the valve core.

However, yours appears to be a single piece valve (non-removable core).



Since the valve is otherwise trash, I would try gently bending it straight using a pair of pliers.  If it breaks, or doesn't straighten you're no worse off, since you'll have to discard it anyway.