Problem resolved by adding <!--more--> in the end of the post and by adding this code
<?php /* Sticky post loop structure. */ ?>
<?php if ( is_sticky() ) : ?>
<div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
<h1><?php the_title(); ?></h1>
<?php the_content( __( '', 'twentyten' ) ); ?>
<?php wp_link_pages( array( 'before' => '<div class="page-link">' . __( 'Pages:', 'twentyten' ), 'after' => '</div>' ) ); ?>
<?php edit_post_link( __( 'Edit', 'twentyten' ), '<span class="edit-link">', '</span>' ); ?>
</div><!-- #post-## -->
after this line in the loop.php
<?php while ( have_posts() ) : the_post(); ?>
and changing this line
<?php if ( in_category( _x('gallery', 'gallery category slug', 'twentyten') ) ) : ?>
to this one
<?php elseif ( in_category( _x('gallery', 'gallery category slug', 'twentyten') ) ) : ?>