404 Error Route 'index.php' not found

Simply change your code to:

<?php
if(isset($_GET['submit']))
{
echo $vbranch = $_GET['branchid'];
}
?>
<form method="get" action="">
<input type='text' id = 'branchid' name='branchid'>
<input type='submit' name='submit' value='View Report'>
</form>