There are several reasons why dry, dead patches of grass may appear in your lawn, such as plant disease, insects, or competition from neighboring plants. Whatever the cause, a dead patch of grass is never desirable and can be taken care of in a couple of different ways.

Make sure to establish a good healthcare plan for your grass. Cut back any overgrown bushes or plants that are choking your grass out. Make a schedule to fertilize your grass twice a year and aerate periodically to prevent thatch build-up and compact soil. Watering and mowing are perhaps the most important steps to keeping your lawn green.

However, there are times when dry patches still appear, despite our best efforts. If you are repairing a large patch of grass, make sure you have all the proper tools first. During the spring months, make sure to mow the grass and remove all clippings before you put down any seed. This way, the seeds will be directly on the ground. Rake out the area until it is level and place down a thick layer of seed. Cover the seeds with a thin layer of topsoil or compost. Lightly water the area.

When choosing seed, make sure to choose one that matches the rest of your lawn! Once the seeds have begun growing, wait until your grass is 3 inches high before you mow. 

If you are in a time crunch, you can also repair the lawn using sod. Laying sod is very convenient as it can be done at any time of the year. Once you have the sod cut to size and the area prepared (same way as above), press it firmly into the soil. Water often until the roots grow into the soil. 

Dry patches are unsightly, but they should not take too much time to repair. Your lawn can be looking its best in no time at all!

Sources: https://www.bhg.com/gardening/yard/lawn-care/repair-the-lawn/