title: npm start stopped working on react project
body: <p>I've been working on a project using React.js 
  It used to work fine on localhost:3000 but suddenly this has stopped working. 
  The commands I did before was</p>
  
  <ul>
  <li>sudo npm run bundle </li>
  <li>sudo npm start</li>
  </ul>
  
  <p>And then my project was running. But now it says localhost refused connection. Message in the console:</p>
  
  <blockquote>
    <p>"Failed to load resource: net::ERR_CONNECTION_REFUSED". Any ideas why? </p>
  </blockquote>
  
  <ul>
  <li>I have checked that <strong>localhost:3000</strong> not occupied </li>
  <li>I have checked that Im working in the correct folder and all files seems * to be present</li>
  <li>I have checked that Im using the latest <strong>npm</strong> and <strong>node</strong> version</li>
  </ul>