You Query:
$u = "UPDATE player_registration SET `name`='$_POST[inputname], `surname`='$_POST[inputsurname], `contact_number`='$_POST[inputcontact]', `email`='$_POST[inputemail]', `position`='$_POST[inputpos]', `username`='$_POST[inputusername]', `password`='$_POST[inputpassw]' WHERE ID = $_POST[player_id]"; mysql_query($u) or die (mysql_error());
check colored part one quote is missing. rectify it to:
$u = "UPDATE `player_registration` SET `name`='$_POST[inputname], `surname`='$_POST[inputsurname]', `contact_number`='$_POST[inputcontact]', `email`='$_POST[inputemail]', `position`='$_POST[inputpos]', `username`='$_POST[inputusername]', `password`='$_POST[inputpassw]' WHERE ID = $_POST[player_id]"; mysql_query($u) or die (mysql_error());