How can I “reset” an Arduino board?

Question

I\'ve uploaded a sketch to an Arduino Uno whose loop is something like this:

void loop(){
    Serial.println(\"Hello, World!\");
}

So, now,

Answer 1

I also had your problem,and I solved the problem using the following steps (though you may already finish the problem, it just shares for anyone who visit this page):

1. Unplug your Arduino
2. Prepare an empty setup and empty loop program
3. Write a comment symbol '//' at the end of program
4. Set your keyboard pointer next to the '//'symbol
5. Plug your Arduino into the computer, wait until the Arduino is completely bootloaded and it will output 'Hello, World!'
6. You will see the 'Hello, World!' outputting script will be shown as comment, so you can click Upload safely.