Before one month my site completely had completely disappeared from search engine.. But suddenly my website appeared in search engine at top place.. Unfortunately site has again removed from search engine... What is problem? Is something wrong with my site?
hmm... it seem to be normal for new sites with don't have much quality links supporting the content or maybe its not search engine friendly nor user friendly.
How new is the site? Do you have original content on the site? I suspect this could happen if malware was on the site or if the site has issues with crawling/code. Best recommendation I can give you is to use Google Webmaster Tools and check on crawling errors, malware, etc.
My site age is 2 years and 1 months.. What do u mean crwaling/ code? Where it is? I use google webmaster, there is not Crwaling or Malware errors found. No what to do?
If you want answers why don't you give us your URL? Otherwise people are simply going to throw out wild guesses and send you on a wild goose chase.
your website is not stable in search engines, means you don't have quality back links. Build high quality back links for your website. SEO friendly websites with quality back links improve their position slowly in search engines and after getting a good rank, remain stable there and improve more, but not down.
Have you checked your contents? Whether it is copied or you have copied from others? Google will not give ranking to copied posts.
Last year i too had the same problem....i was too perplexed and couldnt find a reason. Finaly i just continued its SEO and few days back again my site was ranked well.
I think this happen just because of new search algorithm and you site is under updating ..so wait and watch.
your website is not stable in any search engines,so you build high quqlity and high page rank back links for your website. and need SEO work for your site.