Fix corrupted serialized Envira Gallery Lite data.

fix-envira-gallery.php

<?php
/**
 *
 */
global $wpdb;
$results = $wpdb->get_results( "SELECT * FROM {$wpdb->prefix}postmeta WHERE meta_key='_eg_gallery_data'" );

foreach ( $results as $key => $row ) {
	$data = $row->meta_value;
	$data = preg_replace_callback(
		'!s:(\d+):"(.*?)";!',
		function ( $matches ) {
			return 's:' . strlen( $matches[2] ) . ':"' . $matches[2] . '";';
		},
		$data
	);

	$data = unserialize( $data );

	// The following was missing in my case.
	$data['config']['justified_margins']    = 1;
	$data['config']['lazy_loading']         = 0;
	$data['config']['lazy_loading_delay']   = 500;
	$data['config']['justified_row_height'] = 150;

	$data = serialize( $data );
	$wpdb->query(
		$wpdb->prepare(
			"
				UPDATE $wpdb->postmeta
				SET meta_value = %s
				WHERE meta_id = %s
			",
			$data,
			$row->meta_id
		)
	);
}