Question
I live in Jacksonville FL on a lake; I have a huge front lawn.  Last fall I developed
what was diagnosed by my lawn company as brown patch fungus; they treated
it; it didn't improve; in fact it spread; they treated it again; and then the weather
turned very cold for about a week; this is 2/28 and most of the entire lawn is
brown, very little green.  Do you think it will come back?

Answer
From what you say, it is unlikely to expect the lawn to recover. Because of the brown patch I assume that the grass is St. Augustine. Chemicals are designed and tested to make sure that they work. When we do not get the expected results, it is usually a case of wrong diagnosis, wrong chemical, wrong application rate or wrong timing. I strongly advise you to get an accurate diagnosis of what is your lawn problem and set about remedying that. Seek the assistance of your County Extension Agent. After that, you will be able to start your new lawn with greater confidence.