Google Sitemap doesn't work

I am new to wordpress. I got the Yoast SEO plugin. Not knowing that it would give me a site map, I got Google XML site maps and made a site map. Then I tried to use Yoast SEO to upload to google webmaster tools. It didn’t work. I went back into Yoast SEO and clicked on “You can find your XML Sitemap here”. It sends me to a page in my site, with my background image, that says:

OOPS! THAT PAGE CAN’T BE FOUND.
It looks like nothing was found at this location. Maybe try one of the links below or a search?
Search for:
RECENT POSTS

etc…

The url is http://www.lawrencejennifer.com/sitemap_index.xml

Not sure if I have a conflict with the previously constructed site map? I have deactivated the google xml site map plugin, but it still doesn’t work.

Can anyone help? BTW, I am essentially code-illiterate, but am trying to learn…

Thanks!