problems with yoast seo and google webmaster

I cretaed a site map using yoast seo and submitted to google. google returns crawl error for 20 pages as url not found
My domian is not new domain it was under use by another person and then he didn’t renew it. so my sitemap includes page links for previous author created posts i guess… Is it ok to get this page not found error also suggest which is better yoast seo sitemap or google sitemap plugin
my site is http://www.geekgyan.com