I am using node 8.11.1 along with angular 6, locally on windows 10. In my node `app.js` I have 

```
//SERVER LISTEN
app.listen(3000, ()=>{
  console.log('Server running on port 3000');
});

```

at the bottom and I run my node using nodemon. 

I did not installed any program recently, and node/angular worked perfectly. 

I did some editing on a query code in node, some minor editing and then copied some files to an external drive. I did not remove the files, I copied them, so they are still on my laptop too, I can see them. These are the last steps I can recall. 

And yet, I do `nodemon`, now I get

```
events.js:183
      throw er; // Unhandled 'error' event
      ^

Error: listen EADDRINUSE :::3000

```

What happened ? Is there an explanation ? How can I get node to run on port 3000 again? Thanks