After a vigorous exercise, my quads are extremely sore, causing my legs to buckle when i walk. what steps do i take to heal, and prevent more injury?

Don't push so hard!: 1st drink plenty of water to rehydrate. Then take it easy ie no exercise for next several days until you're better. Next time, don't push so far, so fast, so hard. Yes, you still need to exercise but not to that extent. In meantime, do stretch all your muscles, especially the sore ones. And keep exercising those muscles that don't involve the sore ones.