Burned grass occurs, most of the time, as a result of using a fast-release fertilizer on wet grass. The fertilizer does not have the chance to wash away in time and nitrogen burns the grass. Dog excrement and urine in small and large quantities can also burn grass, and so can road salt, as well as too much sun. Whatever the cause, the burns ruin the visual appeal of the lawn. In order to restore it, you must care for the spots, eradicating both the cause and the effect.
Rake the burned areas, clearing away dead grass. Once the grass is brown, in many cases it has been killed and cannot come back. (For cases where your grass has not been killed, see the Tips section.)
Flood the burned areas with water each morning of the next week, especially if it does not rain. This will clear the excess nitrogen from the root regions of the grass, if this is indeed the problem.
Clear away the top inch of soil. Replace this with an inch of loam to get a fresh start.
Scatter new seed over the loam to beef up your lawn. Without new seed these areas will remain bare and weeds will eventually take over. Place pine straw mulch over the seed to protect it while it germinates and grows.
Water the new grass seed daily, keeping it moist until it begins to grow vigorously. Try to do this in the morning, allowing the grass to dry out during the day. Return to your regular watering schedule when the new grass is established.