What kind of fertilizer did you put down, what was the herbicide? What kind of grass do you have?
Answer these and we can then give you much more details.

What kind of fertilizer did you put down, what was the herbicide? What kind of grass do you have?
Answer these and we can then give you much more details

I used scotts turf builder weed and feed and I have KBG Rye and Fescue, Its a sodden lawn and had it sodded in 2009 and it was installed in October so its a cooler season grass I presume, ? It does great in sept and oct super thick and green....

maybe the burnt parts are the weeds dyeing off from the herbicide in the weed and feed

There are two types of weed and feed. One is a pre-emergent crab grass preventer and the other is a broadleaf weed killer. The pre-emergent one should have been put down over a month ago and it's generally a good product. The other one should never be used. it's idiotic to broadcast spray weed killer over your entire yard. Weeds should be spot treated.

Having said that...
Those scotts products are basically a big bag of salt (not table salt, but a mixture of salts). They need to be watered in or else they'll desiccate what they come in contact with. The idea is the broadleaf weeds have more leaf surface area and hence will absorb more and it will kill them, but if not put down properly, you can also damage your lawn.

There's not much you can now other than to make sure the brown areas have plenty of water. In the future, use normal fertilizer (not weed and feed) and make sure to water after applying it.

HI Kidhorn and I totally 100% agree with everything you said, I try and follow the scotts steps but never fertilize in summer ever unless its Milorganite sp? organic fertilizer I used the crabgrass control in late march and did the weed and feed last thur and it left weird trails of burn on my gorgeous lawn :( I was so upset ugh, anyways Yes I am watering the crap out of it everyday and it is long now its been a week since I cut it and I always cut high..I have NO weeds just a tiny bit of clover near the street so Idk why I even use weed ane ld feed I will NOT being using that again next spring I will use plain fertilizer My neighbors all don't treat their grasses and I get some dandelions near the street and I cut them out by the root LOL :/ so annoying when others around you don't care they cut their lawns on the lowest setting too ..so it poured here in pitt lastnight thank god so put some nitrogen into my lawn instead of tap water It looks to be recovering...tho it is long I am so obsessed I wont look at it when I drive by LOL I don't wanna see the dead areas till it back to normal ahhhhhh I am way to into my lawn..Ty for writing will give update soon

There are a few more types of weed n feeds by scotts. Look on the front of the bag and it will list the % of herbicides in it, what were those?

At my local home depot (florida) I can get 3 different types of scotts weed n feed.

Im trying to see if she put an incompatible chemical on her type of grass.

It was scotts turfbuilder w weed and feed for dandelions and such, I don't have dandelions so I messed up :( luckily my lawn is healthy I core aerate every spring too, so its recovering pretty good, except one side is alittle bad, should I rake it out alittle ?????????????