The soil beneath my grass is so hard and bumpy that it is painful to walk barefoot on it.
Many people have lumpy lawns after the actions of winter weather and from poor lawn management.
Starting over may be the best solution if there is mostly bare soil and not much grass. If the grass is a good variety for your area and is getting plenty of sunlight, fertilizer and water, you will need to work on the soil. Tilling it up and adding lots of organic matter may be best, but the next best thing is to do a core aeration. Soil scientists and turf grass experts recommend that cores a minimum of four inches long be pulled from the soil in a grid pattern every two to three inches in both directions. If the tines on the machine are farther apart, the machine needs to go over the same area multiple times.