google webmastertools is showing 18 urls not found for my blog.How to resolve this error all those urls are active.I have even submitted my sitemap.Can any body help me in resolving this problem.
Your blog must be having downtime or internal linking issues for that to be happening. I would have to review the blog, what is the URL.
I get a 404 error at http://www.talkhealthonline.com/sitemap.xml, what is the URL to your XML sitemap?
I'm new with this.. I agree with Kwyjibo maybe your hosting is down while the SE tried to crawl your pages.... and 404 means or Not Found error message is an HTTP standard response code indicating that the client was able to communicate with the server, but the server either could not find the file that was requested, or it was configured not to fulfill the request and not reveal the reason
It might be due to hosting downtime when the spider tried to crawl your site. Check if it is a 404 error.