I think we all hit a button that takes the entry sometimes.  Go straight back as if you are going to do a new blog, In the empty frame, down on the bottom left hand corner you will see a phrase "Last auto saved" and a time, click on that and what was saved will appear in the frame. It will not be the full blog just what you had typed at the last time it was auto saved. No blog is entirely lost so you can rebuild from there. Hope you can follow these instructions and find you can reassemble your blog that way.

Wonderful!I will try!