Help repair my lawn

I laid down sir Walter buffalo about 2 years ago with about 80mm sandy loam as a base. Lawn looked fantastic and lush went for a holiday came back and lawn was burnt in several places bought it back to life with lots of water and fertiliser but I still have so many patches where the grass will not grow. Can anyone suggest how I get these patches back to grow?

Is the black stuff potting soil?

It’s lawn mix I put down with lawn repair

Gig out small patches from healthy grassed areas and dig them into areas that without grass. This will then speed up the time to cover larger areas without grass.

Grab some runners from somewhere else in the lawn and plant them in the bare patches or buy a roll and cut out patches to fit.
Loosen up the soil in the bare patches with a pitchfork first.

Have you checked that you don’t have lawn grab or something else that is affecting the grass?

Yep have black beetle grubs can't believe it. Sprayed beetle spray all over, then cut out all dead patches and laid new turf down. Also got myself Scott's lawn grub fertiliser. Hope that does the trick.

Glad that helped, looking forward to seeing it recover 😊