There is an issue with wordpress for some users. To keep this from happening again , put in the title for the post, set it as private and then publish it. Then continue and finish the post and when you are ready to have it go live, set it back to public and click "update."
You can try this to recover an earlier draft. In your Dashboard view, on the upper right corner, under the “[name]” is a tab labeled “Screen Options.” http://en.support.wordpress.com/screen-options/ Click it. Here is a list o f the screens where the modules can be hidden:
Posts – Post Tags, Categories, Excerpt, Send Trackbacks, Discussion, Comments, Post Slug, Post Author, Post Revisions
Page – Page Attributes, Recommendations, Featured Image, Discussion, Comments, Slug, Author, Revisions
Select those and return to your Dashboard.
Make sure you select Select Post Revisions and Page Revisions those and return to your Dashboard. Then close the tab.
On the left toolbar, click on either “Pages” or “Posts” depending on what type of document are you are trying to restore.
You can look the last autosave for Posts » Post Revisions > http://en.support.wordpress.com/posts/post-revisions/
You can look in the last autosave for Pages » Page Revisions > http://en.support.wordpress.com/pages/page-revisions/