I checked my website index status in google webmaster tool where i seen the index status of my site is going to be decreased from 23rd June.Previously it will continuously increased.My other website's index status is only increases.what is the problem ..is there any serious issue?
Make sure you have a regular time posting, twice a week for example. make sure you don't have duplicated pages. If not solved the problem in the next 10 days, you should resubmit your site sitemap again. It will be crawled again.
clear all those errors and remove duplicate and unwanted stuff in your site and create a new sitemap and add.
Remove duplicate pages or disallow duplicate urls for getting indexed from Google with the help of robots.txt file. Update sitemap and upload it to server.
You should check all the problems in WMT. check the duplicate title, meta tag, description and also you can validate your site map through online validator and after few days..resubmit your sitemap to WMT and your website. Check your your SERPs whcih will give a clear idea about humming bird update ... that your site is hit or not?? finally also check your backlinking through online tools and remove the useless ones.