PHP Create and Save a txt file to root directory

It's creating the file in the same directory as your script. Try this instead.

$content = "some text here";
$fp = fopen($_SERVER['DOCUMENT_ROOT'] . "/myText.txt","wb");
fwrite($fp,$content);
fclose($fp);

If you are running PHP on Apache then you can use the enviroment variable called DOCUMENT_ROOT. This means that the path is dynamic, and can be moved between servers without messing about with the code.

<?php
  $fileLocation = getenv("DOCUMENT_ROOT") . "/myfile.txt";
  $file = fopen($fileLocation,"w");
  $content = "Your text here";
  fwrite($file,$content);
  fclose($file);
?>

This question has been asked years ago but here is a modern approach using PHP5 or newer versions.

  $filename = 'myfile.txt'
  if(!file_put_contents($filename, 'Some text here')){
   // overwriting the file failed (permission problem maybe), debug or log here
  }

If the file doesn't exist in that directory it will be created, otherwise it will be overwritten unless FILE_APPEND flag is set. file_put_contents is a built in function that has been available since PHP5.

Documentation for file_put_contents