2017 installed recently but now does not work

Hi, Last week I installed 2017 theme, which worked. But since recent days my site pages are blank and in admin it says “theme uninstalled”. I cannot delete it or reinstall it. I want to use the theme, but when I go to appearance on the sidebar in admin and click on themes 2017 says it’s false. Can anyone help?

The page I need help with: [log in to see the link]