Before some days i just change my url in google webmaster tools to solve url canonization problem. Then in next day we just change our web server. Does it effect to site anyway. Because google showing unindex my site now.
well, if both your old and new server are in the same country then you rankings will normally not be affected, i can't tell you more because, don't know much about your website (giving us the URL can help).
I doubt Google would "unindex" your site because of either of those actions. It's more likely you're looking for the wrong domain w/ the SITE: operator. Searching for SITE:WWW.EXAMPLE.COM will only show your URLs indexed w/ www for your domain. Searching for SITE:EXAMPLE.COM will show your URLs indexed w/ and w/out www for your domain. Try the latter first... My guess is that you'll find your URLs still indexed. But as funky said, it's impossible to do anything but guess until you provide us w/ a URL.
I too don't think changing server will affect site rank(Make sure the new server is not a penalized one). Even if some dns confusion is there for few hours after one or two days it will come to normal.
i dont think so that changing server will effect your rankings but while changing server do keep in mind that the links dont get broken which can effect you.So first make the site perfect at new server then change the dns