fix

<?php
     include 'bd/blocks/bd.php';
     $result = mysqli_query($db,"SELECT keywords,description,author FROM page WHERE page='blog'");
     $myrow = mysqli_fetch_array($result);
if(isset($_GET['date']) ){ //&& !empty($_GET['date'])
    $date = $_GET['date'];
}
/*
elseif (!isset($_GET['date']) && empty($_GET['date'])) {
    header("Location: index.php");
    exit;
}*/
else{
//  header("Location: index.php");
    echo("<script>location.href = 'index.php';</script>");
    exit;
}
//$date= "$date";
//$dates=substr($date,0,7);
$dates= date("Y-m", strtotime($date));
$sql="SELECT count(date) c FROM blog WHERE date='$dates' ";
$sql="SELECT count(date) c FROM blog WHERE date like '{$dates}%' ";

$result2 = mysqli_query($db,$sql);
//since the data contain month-year.. you should use other name for this fieldname.

$res=mysqli_fetch_array($result2);
if($res['c']==0){
    echo("<script>alert('no blog found'); location.href = 'index.php';</script>");
    exit;
}
/*
echo mysqli_num_rows($result2);
if(mysqli_num_rows($result2)){
 header("Location: index.php");
    exit;
}
*/
     $date_title=$date;
     $date_begin =$date;
     $date++;
     $date_end=$date;
     $date_begin=$date_begin.'-00';
     $date_end=$date_end.'-00';
 ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
        <meta http-equiv="Content-Language" content="en" />
        <meta name="description" content="<?php echo $myrow['description']; ?>" />
        <meta name="keywords" content="<?php echo $myrow['keywords']; ?>" />
        <meta name="author" content="<?php echo $myrow['author']; ?>" />
        <title><?php echo 'archive for '. $date_title .'';?></title>
    <!-- HEADER -->
        <?php include 'bd/blocks/head.php'; ?>
        <!--ENDS HEADER -->
    </head>
    <body>
    <!-- WRAPPER -->
    <div id="wrapper">


    <!-- navigation & HEADER -->
    <?php include 'bd/blocks/header.php'; ?>
    <!-- ENDS navigation & HEADER-->
    <!-- MAIN -->
    <div id="main">


    <!-- posts -->
    <div id="posts">

        <!-- single-post -->
    <?php
    $sql="SELECT id,text,author,view,img,choose,title,date FROM blog WHERE date > '$date_begin' AND date < '$date_end' ORDER BY id DESC";
       $result = mysqli_query($db,$sql);
        while($myrow = mysqli_fetch_array($result)){
         $let55=explode(" ",$myrow["text"]);
         $me=0;
         $newtxt="";
         while($me<55){
             $newtxt.="".$let55[$me]." ";
             $me+=1;
}
                          printf('
        <div class="post">
            <p class="post-title custom">%s</p>
            <p class="post-meta">%s <span>by %s</span></p>
            <p class="post-comments custom">%s</p><br><br>
            <div class="%s-img"><a href="single.php?id=%s"><img src="%s" alt="" widht="610" height="230"/></a><span></span></div>
            <p class="brief">%s...</p>
            <p><a href="single.php?id=%s" class="more">More</a></p>
        </div>',$myrow["title"] , $myrow["date"] , $myrow["author"] ,$myrow["view"] ,$myrow["choose"] , $myrow["id"]  ,  $myrow["img"] , $newtxt , $myrow["id"]);}
    ?>
        <!-- ENDS single-post -->

        <!-- blog-pager -->
        <ul class="blog-pager">
            <li><a href="#">NEWER</a></li>
            <li><a href="#">OLDER</a></li>
        </ul>
        <!-- ENDS blog-pager -->


    </div>
    <!-- ENDS posts -->

    <!-- sidebar -->
        <?php include 'bd/blocks/side-block.php'; ?>
        <!-- ENDS sidebar -->


        </div>
        <!-- ENDS sidebar -->


    </div>
    <!-- ENDS MAIN -->

    </div>
    <!-- ENDS WRAPPER -->


    <!-- FOOTER -->
    <?php include 'bd/blocks/footer.php'; ?>
    <!-- ENDS FOOTER -->
    </body>
</html>