why my blog suddenly disappear from SERP google…??
Was it a blog, or a splog? If you were posting your own original non-offensive content, are you sure it’s disappeared, or only moved?
There may be several reasons such as Google update its database time to time and keep only those blogs and sites in better SERP whose content is informative and valuable for users.
you need to do more SEO work for your blog to bring it in front of SERP.