Website inaccessible

I’m not able to open my site. I asked the WordPress team of engineers who told me to that this problem was caused due to the themes and hence, to contact the theme author. I’m not able to post/customize/delete or do anything important with it. The last thing I did was upload plugins and change my theme to Wisdom Blog. What should I do to make it run normally again?

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