Collin:

It would really help to me to identify the problem(s), if you would attach photos of your lawn. One photo of the area where the grass is dying and a photo showing the edge of one of the splotches with both the dying area and grass that is still green.

Thank you-

Collin:

From the above two photos, it looks to be me that some of the dying spots have a yellowish or bronze color. The yellow or bronzing of the grass is indicative of "Summer patch" disease. "The disease first appears in the warm weather of the summer, typically after rainy periods or heavy downpours. Saturated soils have been shown to exacerbate disease development." 
Is the soil in your lawn compacted? Is it difficult to push a screwdriver into the soil? Compacted soils also encourage this disease. Aerating the soil will help if compaction is the issue.
The fungicides are only effective against this disease if applied at the early stages of this disease, so applying a fungicide now may save some of the grass if it is not already infected. Fungicides  giving preventative control can be found here.

I hope this helps-

Thank you very much.

Ok-thank you again, very much.

Collin:

I do not think I would strip away all the sod. I would suggest raking all the dead material out of the dead spots and then reseed those areas with a good quality sun/shade grass mix. Rake the grass seed into the ground, we want good seed to soil contact. After seeding keeping these reseeded areas moist, but not not water logged. As soon as the grass begins to come up and the area looks green, reduce the watering to 1" of water per week and continue that until the grass goes dormant. Do Not Apply any fertilizer or weed n' feed to these areas until the grass has been up 30 days and is more that 2" tall. On the subject of mowing, never mow cool season grasses lower than 2" and in the heat of the summer a mowing height of 2.5-3" is preferred. The taller a grass plant goes the deeper its roots grow.

Thank you very much Doug. I will do what you have suggested and hope to see green grass again, if not this fall, in the spring.

If you reseed, please do it this year. In the northern 2/3s of Illinois seeding grass in late August until the middle of September gives us the best new stands of grass. 
Seeding grass in the spring results in the seedling grass trying to compete with the more vigorous spring and summer annual weeds.

Dear Doug,

Collin: 

That looks good. the soft soil is exactly what you want for broadcast seeding your grass seed. After you spread the grass seed take the back of the rake lightly cover the seeds with the loose soil. Then keep these seeded areas moist with daily light waterings, you do not want muddy, and do this until the seedlings  this begin to come up. After that water as needed to prevent the seedlings and young grass from wilting. With the warm temperatures that are expected for this coming weekend, you might want to seed just ahead of any showers forecast for next week with the approaching cold front.