I made a few changes and now the error is:

Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at /home/rgitproj/public_html/vikistin/index.php:10) in /home/rgitproj/public_html/vikistin/index.php on line 38

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/rgitproj/public_html/vikistin/index.php:10) in /home/rgitproj/public_html/vikistin/index.php on line 38
Table 'rgitproj_vikistin.SS_categories' doesn't exist

THIS IS THE CODE

LINE 38:     session_start();

    ini_set("display_errors", "1");

    //init Smarty
    require 'smarty/smarty.class.php';
    $smarty = new Smarty; //core smarty object
    $smarty_mail = new Smarty; //for e-mails

    //select a new language?
    if (isset($_POST["new_language"]))
    {
        $_SESSION["current_language"] = $_POST["new_language"];
    }

    //current language session variable
    if (!isset($_SESSION["current_language"]) ||
        $_SESSION["current_language"] < 0 || $_SESSION["current_language"] > count($lang_list))
            $_SESSION["current_language"] = 0; //set default language
    //include a language file
    if (isset($lang_list[$_SESSION["current_language"]]) && file_exists("./languages/".$lang_list[$_SESSION["current_language"]]->filename))
        include("./languages/".$lang_list[$_SESSION["current_language"]]->filename); //include current language file
    else
    {
        die("<font color=red><b>ERROR: Couldn't find language file!</b></font>");
    }

    //connect to the database

kristopher wrote:

Table 'rgitproj_vikistin.SS_categories' doesn't exist

This means exactly what it says: table SS_categories does not exist. Restore it from a backup, if you one.