Dig up the dirt and put some fresh topsoil in its place. Reseed with seed patch mix and fertilizer, and presto!
Dont buy some of the bagged topsoils, they have the consistency of mulch. Bought a bag of miracle grow topsoil, it was more like miracle mulch Instead. The really cheap stuff that's like $2 a bag at lowes is essentially the stuff the street sweeper dumps out. Sometimes there's rocks in it, or dirt, or wood, or a few nails, or dried sludge.