Website broken after upgrade

I don’t know if this happen because i update the last wordpress version or Gamepress version but after a spammer post on my website mt main page is missing and a text DENEME appear.
Logging into wp-admin all work fine, restore the default theme also work perfect, but if i try to install Gamepress from scratch, an empty page with plain text “deneme” re-appear. I don’t think it has to do with the spammer or someone has defaced my website because default theme and wp-admin work.
Any tips or solution ?