hello friends i am total confusion i didnt change my domain but i changed the server address before changing the server address my site use to come in frist pages in google after changing the adrres the site not showing resluts in google more over i didnt make any change in desgin and content also change of server makes diiference? how to over come this type of promblem pls suggest............
there should be absolutely no effect unless your new server has a blacklisted IP, i.e. a disreputable host which is known only to provide hosting to spammers etc. Google follows dns to reach your hostname and your IP should not make a difference. However, if dns took a long time to propogate and google could not reach your site when it crawled this may have a temporary effect. This is why it is a good idea to leave the content on the old server for a few days as well after you have copied it to the new server
If you changed from US address to US address the chance to see bad results is very low, but if you changed the address to UK let's say, you may see some differences in google serps.
How long ago did you change the server? It can take up to 48 hours for your new IP address to get cached in all the routers on the internet (depending on your DNS set up). So Google may have lost your pages until their next crawl if you didn't leave the old site up with the new one for a few days. I'd be patient if you didn't change any URLs or content, as your rankings should come back the next time Google crawls your site.
There are many things that influence geographic targeting in search. However, server IP is definitely not the most important.
It may affect you for a week or two, but you'll be fine after that. I've been there done that. As long as you have a quality site with backlinks you'll be fine.