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