how to fix cellar entrance that had water damage
 

My cellar entrance from my backyard has been a victim of water damage
that has spanned decades. The cement has become compromised and the
sides are literally crumbling. The stairs seem like they haven't been
damaged so how do I go about repairing the walls on either side of
this entrance? It seems like both sides of the stairs will need to be
torn down and rebuilt. To add to the problem I believe I need to have
the back of my house regraded because it is too level and that is
probably the source of the problem. There is a cement walkway around
the cellar so I suppose that needs to be removed. =Is this something
I can do myself or should I get a contractor to make sure it's done
correctly since there is the grading issue to contend with?

how to fix cellar entrance that had water damage
 

I guess what I'm really asking is if the water has found it's way from
the outside to the inside through the cellar doorway (when it rains it
streams down the side of the walls to a drain) is it even possible to
"fill the cracks" and make it water tight again? I'm guessing no,
since the water is already inside the wall.