Replace steps?

Question:

Answers:
The whole set of steps (stairs) or just several steps out of the set?
If it's the whole set and they are wood, you have to get what's called step tread (or stair tread) for the sides (supports) and then the cross planks (which you would actually consider the steps themselves). The step tread is what looks kind of like a big wooden saw blade before you put the planks across it, and would have to be the right length to go from the doorway to the floor or ground.

If it's just a couple (or several) steps, then just buy 2X's (or one long one) that are/is the same width as the existing steps, and then cut to fit the width of the stairs (length of the steps). Pry the old steps off and nail or screw the new ones down.