Cut off the nosing (probably 2x10 or ply) and put new risers on flush with the top of where the tread was. Put new tread on top, that way the rise of the treads stays the same and you don't have to guy anything ( first and last step will be 3/4" higher than before)
Here's some oak steps I did a few weeks ago that were carpet
Here's some oak steps I did a few weeks ago that were carpet

