I was checking on Google webmater tool for my blog site to see if there's any indication on why my blog traffic decreased to half in one day and i saw 43 Not Found crawl errors and 5 in Sitemap Not Found errors. The 5 Not Found errors in Sitemap were the links to categories. I guess I renamed categories that's why google can't find the links. As for the 43 other Not Found errors, I see blog post titles that contains (' .) EX: McDonald's, O.N.E.  They weren't found by google crawler. Blog post with /CachedYou at the end and blog posts with /www.example.com attached at the end, they weren't found by Google crawlers either. My question is how do I correct those Not Found Errors?

Thanks