That format is probably not a format that strtotime()
can interpret. Try using DateTime::createFromFormat()
instead:
$dt = DateTime::createFromFormat('g:i:sa d/j/Y', '2:28:15am 28/11/2013');
echo $dt->format('Y-m-d H:i:s');
I had to guess at the exact formatting of your dates. But you can easily edit that by using the appropriate formatting options listed here.