Create button to reset the counter

Solution 1:

First of all you need to create a new button with that functionality of resetting your counter variable. Wrap your center widget with a column and add a new button like this:

Column(
      children: [
        Center(
          child: Text(
            "Contador\n$count",
            textAlign: TextAlign.center,
          ),
        ),
        ElevatedButton(
          child: const Text("Reset Counter"),
          onPressed: () {
            setState(() {
              count = 0;
            });
          },
        ),
      ],
    ),

In order to see the counter updating on your screen you have to call the increment method inside of setState() so the framework schedules a rebuild!

  void increment() {        
    setState(() {
     count++;
    });
  }

I suggest you do some tutorials on the official flutter site to get started with the core fundamentals of flutter - happy coding! :)