Hello,
it seems like you didn’t closed a PHP syntax.
The footer.php content is this:
<?php
/**
* The template for dispalying the footer.
*
* @package WordPress
* @subpackage illdy
*/
?>
<?php
$display_copyright = get_theme_mod( 'illdy_general_footer_display_copyright', 1 );
$footer_copyright = get_theme_mod( 'illdy_footer_copyright', __( '© Copyright 2016. All Rights Reserved.', 'illdy' ) );
$img_footer_logo = get_theme_mod( 'illdy_img_footer_logo', esc_url( get_template_directory_uri() . '/layout/images/footer-logo.png' ) );
?>
<footer id="footer">
<div class="container">
<div class="row">
<?php
$the_widget_args = array(
'before_widget' => '<div class="widget">',
'after_widget' => '</div>',
'before_title' => '<div class="widget-title"><h3>',
'after_title' => '</h3></div>'
);
?>
<div class="col-sm-2">
<?php
if( is_active_sidebar( 'footer-sidebar-1' ) ):
dynamic_sidebar( 'footer-sidebar-1' );
else:
the_widget( 'WP_Widget_Text', 'title='. __( 'Products', 'illdy' ) .'&text=<ul><li><a href="'. esc_url( '#' ) .'" title="'. __( 'Our work', 'illdy' ) .'">'. __( 'Our work', 'illdy' ) .'</a></li><li><a href="'. esc_url( '#' ) .'" title="'. __( 'Club', 'illdy' ) .'">'. __( 'Club', 'illdy' ) .'</a></li><li><a href="'. esc_url( '#' ) .'" title="'. __( 'News', 'illdy' ) .'">'. __( 'News', 'illdy' ) .'</a></li><li><a href="'. esc_url( '#' ) .'" title="'. __( 'Announcement', 'illdy' ) .'">'. __( 'Announcement', 'illdy' ) .'</a></li></ul>', $the_widget_args );
endif;
?>
</div><!--/.col-sm-3-->
<div class="col-sm-2">
<?php
if( is_active_sidebar( 'footer-sidebar-2' ) ):
dynamic_sidebar( 'footer-sidebar-2' );
else:
the_widget( 'WP_Widget_Text', 'title='. __( 'Information', 'illdy' ) .'&text=<ul><li><a href="'. esc_url( '#' ) .'" title="'. __( 'Pricing', 'illdy' ) .'">'. __( 'Pricing', 'illdy' ) .'</a></li><li><a href="'. esc_url( '#' ) .'" title="'. __( 'Terms', 'illdy' ) .'">'. __( 'Terms', 'illdy' ) .'</a></li><li><a href="'. esc_url( '#' ) .'" title="'. __( 'Affiliates', 'illdy' ) .'">'. __( 'Affiliates', 'illdy' ) .'</a></li><li><a href="'. esc_url( '#' ) .'" title="'. __( 'Blog', 'illdy' ) .'">'. __( 'Blog', 'illdy' ) .'</a></li></ul>', $the_widget_args );
endif;
?>
</div><!--/.col-sm-3-->
<div class="col-sm-2">
<?php
if( is_active_sidebar( 'footer-sidebar-3' ) ):
dynamic_sidebar( 'footer-sidebar-3' );
else:
the_widget( 'WP_Widget_Text', 'title='. __( 'Support', 'illdy' ) .'&text=<ul><li><a href="'. esc_url( '#' ) .'" title="'. __( 'Documentation', 'illdy' ) .'">'. __( 'Documentation', 'illdy' ) .'</a></li><li><a href="'. esc_url( '#' ) .'" title="'. __( 'FAQs', 'illdy' ) .'">'. __( 'FAQs', 'illdy' ) .'</a></li><li><a href="'. esc_url( '#' ) .'" title="'. __( 'Forums', 'illdy' ) .'">'. __( 'Forums', 'illdy' ) .'</a></li><li><a href="'. esc_url( '#' ) .'" title="'. __( 'Contact', 'illdy' ) .'">'. __( 'Contact', 'illdy' ) .'</a></li></ul>', $the_widget_args );
endif;
?>
</div><!--/.col-sm-3-->
<div class="col-sm-4">
<?php if( $img_footer_logo ): ?>
<a href="<?php echo esc_url( home_url() ); ?>" title="<?php echo esc_attr( get_bloginfo( 'name' ) ); ?>" class="footer-logo"><img src="<?php echo esc_url( $img_footer_logo ); ?>" alt="<?php echo esc_attr( get_bloginfo( 'name' ) ); ?>" title="<?php echo esc_attr( get_bloginfo( 'name' ) ); ?>" /></a>
<?php endif; ?>
<?php if( $display_copyright == 1 ): ?>
<p class="copyright"><span data-customizer="copyright-credit"><?php printf( '%s <a href="%s" title="%s" target="_blank">%s</a>.', __( 'Theme:', 'illdy' ), esc_url( 'https://colorlib.com/wp/themes/illdy' ), __( 'Illdy', 'illdy' ), __( 'Illdy', 'illdy' ) ); ?></span> <?php echo illdy_sanitize_html( $footer_copyright ); ?></p>
<?php else: ?>
<p class="copyright"><?php echo illdy_sanitize_html( $footer_copyright ); ?></p>
<?php endif; ?>
</div><!--/.col-sm-3-->
</div><!--/.row-->
</div><!--/.container-->
</footer><!--/#footer-->
<?php wp_footer(); ?>
</body>
</html>
You should have a look here about the backup practices, but it mostly depends on what you want to modify:
https://codex.wordpress.org/WordPress_Backups
For an issue like this, all you need is to have a local duplicate on your computer of all the themes files, but in this case downloading the theme again would get you the initial files back.
Best regards