Central Florida…What can I do here?

Central Florida, US
I really need help fixing my lawn this year.

Last year my lawn was nice, full and green grass, I cut my grass short and afterwards my sprinkler system was down for a week in end of July and that was enough to kill it 🙁

Now it’s full of weed and no grass, I started to remove the weed yesterday but I thought to ask for tips.

I have a lot of trees/shade in my front yard.