When your blog site no longer listed at SERP, it means your blog site is penalized.

What to do?

Step 1: Sign in your Google Webmaster Tools account.

Step 2: Open up the 'Message' box, read and follow the instructions given.

Step 3: Request for reconsideration.

Step 4: In the Webmaster Tools 'Dashboard' page, down under at the left column; click 'Labs'

Step 5: Click 'Fetch as Googlebot'

Step 6: Enter your blog's post html file link
(to obtain it, hover your mouse insertion point onto your blog's post TITLE, mouse's right click, select 'copy link location', left-click the selected ''copy link location', and finally paste into the box)

Fetch as Googlebot
With Fetch as Googlebot you can see exactly how a page appears to Google.

http://yourblogsite.blogspot.com/ [continue the remaining] [Fetch button]
Type the URL to fetch or leave blank to fetch the homepage.
If you leave the box blank, googlebot will crawl the homepage.

Would be much better if you enter all of your blog's post TITLE html URLs.

Watch the related videos;

What should I do if I don't know why I'm penalized?

Requesting reconsideration using Google Webmaster Tools