Sizde çalışırsa geri dönersiniz.
$cookie = "cookie.txt";
$ch = curl_init();
curl_setopt($ch,CURLOPT_COOKIEJAR,$cookie);
curl_setopt($ch,CURLOPT_COOKIEFILE,$cookie);
curl_setopt($ch,CURLOPT_URL,"http://ask.fm/login");
curl_setopt($ch,CURLOPT_FOLLOWLOCATION,1);
curl_setopt($ch,CURLOPT_USERAGENT,'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.13) Gecko/20080311 Firefox/2.0.0.13');
curl_setopt($ch,CURLOPT_REFERER,"http://ask.fm");
curl_setopt($ch,CURLOPT_RETURNTRANSFER,1);
$html = curl_exec($ch);
$dom = new DOMDocument();
$dom->loadHTML($html);
$xp = new DOMXpath($dom);
$nodes = $xp->query('//*[@id="loginForm"]/input[2]');
$token = $nodes->item(0)->getAttribute('value');
curl_setopt($ch,CURLOPT_POST,1);
// mail adresinizi ve şifrenizi girin.
curl_setopt($ch,CURLOPT_POSTFIELDS,"authenticity_token=".$token."&login=mail_adresiniz&password=sifreniz");
curl_setopt($ch,CURLOPT_RETURNTRANSFER,1);
curl_setopt($ch,CURLOPT_FOLLOWLOCATION,1);
$son = curl_exec($ch);
echo $son;
// bu kısımdan sonraki kodu denemedim. kod çalışmazsa kaldırırsınız.
// logout işlemi olursa sonraki girişleri izin verir diye ekledim.
curl_setopt($ch,CURLOPT_URL,"http://ask.fm/logout");
curl_setopt($ch,CURLOPT_FOLLOWLOCATION,1);
curl_setopt($ch,CURLOPT_RETURNTRANSFER,1);
curl_exec($ch);
curl_close($ch);