I got new sod maybe about a month ago I've only cut it once and the top of the grass was all green but underneath is brown! I really don't want this grass to die it cost a lot to get it in. What can I do to get this grass happy!

Cut it ? Did you talk to the sod company before ? Often it needs to grow for some time prior to cutting.

Also how is the watering ? Feeding ? Of the grass, is it being done regularly ?

What type of sod? Bermuda typically only green in the top 1/2"

Was it rolled out when installed, what it watered according to schedule?

I'm not sure what kind of grass I watered it a lot every day for two weeks after that it rained a lot for the next two weeks then I cut it. Is one month not long enough to to wait to cut the grass? What do you mean by Fred the grass

I'm not sure what kind of grass I watered it a lot every day for two weeks after that it rained a lot for the next two weeks then I cut it. Is one month not long enough to to wait to cut the grass? What do you mean by Fred the grass
Not Fred, FEED the grass. Did you fertilize the grass ?

Feed* sorry I was doing a talk to text haha.

I found out it was Kentucky Blue Peat Sod and I have not fertilized it at all

I'm in a similar boat - I planted my own grass in May, it grew beautifully, and I think I let it grow too long after the first mowing. All brown underneath, and it didn't recover. Plus it has been very very hot here.

Sod has more variables. The roots have to 'take' to the soil underneath, which must be worked loose, and the sod well tamped down so the roots can grab. Otherwise air pockets dry out and it dies.
But I think you did wait too long to mow, if you waited a month. Sorry. Try scattering seed over it and watering every day again.

I tried a bit of fertilizer if it helps I'll keep up on it and I'll wait to more it again too. My mower cuts too short I'll try raising it too and watching the yard to make sure it's not too wet or dry. My home depot didn't sell a ph testing kit or I would have done that too4843048430

You don't mention if it was tamped down (rolled) or not to make it adhere, nor if you hired someone or installed it yourself.
Fertilizer isn't going to help if it's dead.

I installed it myself, I rolled it down, it's not brown all over and dead or dried out. It's just a brown tinge close to the base of the sod and green tips.

I installed it myself, I rolled it down, it's not brown all over and dead or dried out. It's just a brown tinge close to the base of the sod and green tips.
Needs to be errated. I used to walk all over my lawn in golf shoes. Either that or rent a roller with picks on it.
Cks