Looking at txt files within a folder...

The original format is January.

The number format for month is 01.

<?php
    $month='January';
    $nmonth = date('m',strtotime($month));

echo "
<p>The original format is $month.</p>
<p>The number format for month is $nmonth.</p>
";

?>

Using this code helps make sorting months a bit easier. Again, this may not be the only way to do this, OR the best. Have a look online in the usual places