My Terrible Yard, mud, and sand.

So quick background. I'm not into the greenest grass competition, and my yard absolutely has torpedo already from river sand that was brought in by a neighbor.

My backyard sucks. Not level, few holes, and my drainage is awful. After the 10" of snow, my backyard is straight mud. Is it worth it for me to bring in some sand to attempt to level my yard, or will I be wasting money since my yard is like a marsh and grass won't be growing anytime soon?