mysterious permalink malfunction

Firstly, I am a complete novice trying to create my own site, so apologies.

My problem is my permalinks; they do not work from the site. If I type the permalink into the browser, the correct page comes up (whether or not I have a single.php template in the directory?). If I click on the post title, it goes straight to the 404. I don’t know if this is relevant or not, but the archives links work fine.

My site link is:
https://fromthebigtable.theyellowhammertradingcompany.com/

My single.php is: (and I know it’s junky)

<?php get_header(); ?>

	<div id="adverts">
	</div>			

		<div id="main_content">
			<?php if(have_posts()) : ?><?php while(have_posts()) : the_post(); ?>

			<div class="post_entry" id="post-<?php the_ID();?>">

				<h2><a href=”<?php the_permalink(); ?>” title="<?php the_title(); ?>"><?php the_title(); ?></a></h2>

					<div class="post_date">
						<h3><?php echo get_the_date( $d = 'F j | Y' ); ?></h3>
					</div>

					<div class="post_content">
						<?php the_content(); ?>

						<p class="postmetadata">
<?php _e('Filed under:'); ?> <?php the_category(', ') ?> <?php _e('by'); ?> <?php  the_author(); ?><br />
<?php comments_popup_link('No Comments ?', '1 Comment ?', '% Comments ?'); ?> <?php edit_post_link('Edit', ' | ', ''); ?></p>

					</div> <!post content>

					<div class="post_page">

					</div>

				</div> <!post entry>

						<?php endwhile; ?>

						<?php endif; ?>

			</div> <!main content>

		<div id="navigation_sidebar"><!*vertical*>
			<?php get_sidebar( 'navigation_sidebar' ); ?>
		</div><!navigation sidebar>

<?php get_footer(); ?>

Any help is much appreciated. I’ve searched the forum until my eyes hurt.