My homepage was all the sudden dropped, Why?

I have a website that has been up and running for months now and my home page was listed on the first page of google for a few different keywords and all the sudden when I checked to see how many pages were indexed the one difference was my homepage isn't indexed anymore.

I also checked the keywords and the home page isn't even in the top 10 anymore.

Why could this be?

 

Same thing happened to me, found out that another site is using a 302 Redirect along with a Meta Refresh 0 tag. So as of now my site is gone from Google, or the index page at least, tried removing the offenders page but the meta refresh 0 tag prevents me from doing so. This might be the same problem in your case, a site doing a 302 redirect basically page jacking making Google think that their page is the real one.

Adding the <base> tag to all pages of your site (especially the index page) might help you..

 

how long did it occur? and had you done anything which is unfriendly with your site?

 

Meta tag analysis is the most important role to index the pages in search engines. Please check it properly