By default, you do not need a backup plugin or backup service to restore an individual WordPress Page or Post as WordPress has a feature called the WordPress revision history for anyone who publishes content. If you've deleted a part of your Page or Post, you can use the WordPress Revisions feature to try and recover those deletions and/or changes.
Most do not know or they forget that WordPress automatically saves all the changes you make to your Posts and Pages. You can undo those changes and go back to an earlier version at any time. This is called the WordPress Revisions feature and has been a part of WordPress since WordPress version 2.6.
WordPress will store a post as a revision every time you click the "Save as Draft" button or on each auto-save of the post or page. This auto-save feature happens every 60 seconds as a special revision. Older auto-saves are replaced by new auto-saved revisions.
Revisions shows up in the Publish section on the post editing screen. You can also display revisions below the post editor by clicking Screen Options and ticking the box next to Revisions.
The Revisions module will not show until there are revisions to view.
By default, Post Revisions are enabled in WordPress. So please make sure you have not disabled them in the site's wp-config.php file:
If WordPress did not save the revisions, and if you just want that single page/post, what you could do would be to just migrate the site that includes the post that you need on your local machine (using something like XAMPP, WAMP, etc.) or in a sub-directory on your server.
Then after you have the site migrated just log in and use the WordPress "export" tool. Then you can select which page you want to export. (You'll want to narrow down to the post or page you need by using the available drop down options. The "Start date" and "End date" are key options to use. But they all help narrow down the article that you need.) Then after you have the .xml file, you can import it back to the live site.
Importing Posts or Pages:
Another issue that we see from time to time is WordPress users accidentally deleting pages/posts. When you delete a page or post, it is automatically sent to the page or post trash folder. And by default, you can recover it for up to 30 days after it was deleted.
To recover a page or post, go to the Pages -> All Pages (or the Posts -> All Posts) menu item in the WordPress dashboard menu. Once there, you need to select the "Trash" tab at the top and that will list the pages or posts in the Trash bin.
Then after click the Trash bin tab, you should see a list of deleted pages or posts:
If the page or post you want to restore is listed there, then hover your mouse/cursor over that page/post title and you will see the option to "Restore" it.
Once you restore the page/post, go back to the Pages -> All Pages (or Posts -> All Posts) and you should be able to find that page/post listed there.