I always do experiments on test blogs so, I created a lot of mess with these test blogs and one day I decided to delete them and I did that. After some days, I noticed that there's a link on my Dashboard like this:
So, I clicked Show all link and suddenly all of my Deleted blogs appeared again.
As you can see that there's an option Undelete this blog with every deleted blog. I clicked on Undelete this blog link of one of my deleted test blogs and Whoa!, my deleted blog is back again on my Dashboard. Hurray!
All posts of my recovered blog are there, layout is completely intact. You can also follow this simple method to recover your deleted blog.
Remember: Whenever you delete a blog, don't delete your account.