I have a Wordpress site that has been indexed. I have set "No Index" to Archive, Category, Tag and Author pages.
I am seeing pages which I didn't create being indexed like:
domain.com/page/2/?p=xyzabc
domain.com/page/3/?p=xyzabc
domain.com/page/4/?p=xyzabc
Each of these pages would display 10 of my posts, so it looks somewhat like a post archive.
Question:
It sounds like you caught a WP virus. You can find plugins that provide "anti-virus" - install and run them.
Also, it's likely your server files were corrupted. I suggest downloading the WordPress source files and comparing it to your server so you can safely delete files that don't belong.
If that's the case.