to create a change password page for user in WordPress

just save the code into your current theme directory

Create new page in wp-admin/page name it as change

select template “change password”

publish it. thats all its done .

code 

<?php
/* Template Name: change password */
global $current_user;
get_currentuserinfo();
require_once( ABSPATH . WPINC . '/registration.php' );
if ( !empty($_POST) && !empty( $_POST['action'] ) && $_POST['action'] == 'update-user' ) {
	/* Update user password */
	if ( !empty($_POST['current_pass']) && !empty($_POST['pass1'] ) && !empty( $_POST['pass2'] ) ) {
		if ( !wp_check_password( $_POST['current_pass'], $current_user->user_pass, $current_user->ID) ) {
			$error = 'Your current password does not match. Please retry.';
		} elseif ( $_POST['pass1'] != $_POST['pass2'] ) {
			$error = 'New passwords do not match. Please retry.';
		} elseif ( $_POST['pass1'] = $_POST['current_pass'] ) {
			$error = 'New passwords and old Password should not be same.';
		}elseif ( strlen($_POST['pass1']) < 6 ) {
			$error = 'New Password has to be minimum 6 characters';
		} elseif ( false !== strpos( wp_unslash($_POST['pass1']), "\\" ) ) {
			$error = 'Password may not contain the character "\\" (backslash).';
		} else {
			$error = wp_update_user( array( 'ID' => $current_user->ID, 'user_pass' => esc_attr( $_POST['pass1'] ) ) );
			if ( !is_int($error) ) {
				$error = 'An error occurred while updating your profile. Please retry.';
			} else {
				$error = false;
			}
		}
		if ( empty($error) ) {
			do_action('edit_user_profile_update', $current_user->ID);
			wp_redirect( site_url('/change/') . '?success=1' );
			
		}
		
	}
}
?>

<?php get_header(); ?>
<div class="leftContent">


	<?php while ( have_posts() ) : the_post(); ?>
				<div class="post" id="<?php the_ID(); ?>">
                    <div class="postHead">
                        <h2><?php the_title(); ?></h2>
					<div class="postMeta">
					</div>
				</div>
     <div class="postContent">
				<?php if ( !empty($_GET['success']) ): ?>
                            <div class="message-box message-success">
                                <span class="icon-thumbs-up"></span>
                                Profile updated successfully!
                               
                            </div>
                <?php endif; ?>
                
                <?php if ( !empty($error) ): ?>
                            <div class="message-box message-error">
                                <span class="icon-thumbs-up"></span>
                                <?php echo $error; ?>
                            </div>
                <?php endif; ?>

				<form method="post" id="adduser" action="">

					<table>
                    <tr>
                        <td>
                            <label for="current_pass">Current Password</label>
                        </td>
                        <td>
                            <input class="text-input" name="current_pass" type="password" id="current_pass">
                        </td>
                     </tr>

					<tr>
                        <td>
                    	<label for="pass1">New Password</label>
                        </td>
                        <td>
						<input class="text-input" name="pass1" type="password" id="pass1">
						 </td>
                     </tr>
					<tr>
                        <td>
                    	<label for="pass2">Confirm Password</label>
                        </td>
                        <td>
						<input class="text-input" name="pass2" type="password" id="pass2">
						 </td>
                     </tr>
                     </table>

<?php
// action hook for plugin and extra fields
do_action('edit_user_profile_update', $current_user);
?>
					<p class="form-submit">
						<input name="updateuser" type="submit" id="updateuser" class="submit button" value="Update profile">
						<input name="action" type="hidden" id="action" value="update-user">
					</p>
				</form>

	<?php endwhile; ?>

	</div><!-- .main-column -->
</div>
</div>
	<?php get_sidebar(); ?>


<?php get_footer(); ?>

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