I have a query related to web server migration and corresponding effects on search engine rankings. I have a website of my client for which I was doing SEO for quite some time and getting some pleasant search engine rankings for the same website. Recently he migrates his web server without notifying me and instantly I observed a major downfall in search engine rankings in Google. I have lost the rankings on almost all the keywords. My question is, is this downfall in rankings is due to server migration as that website was ranked on top search engine result pages before the server migration? If this is the reason of downfall, then how can I retain those rankings and how long it will take?? Thanks in anticipation.