[Plugin: SOPA Strike] It did not do anything.

jswinburn, access your site using FTP software. Else if you have a cPanel account, logon using cPanel. Go to the the folder where wordpress is installed. Under wordpress folder, you will have wp-content/plugins folder. In that you will find a folder called ‘sopa-strike’ delete that folder. Then try to access your wp-admin as normal. Hope this helps.

PS: Folder = subdirectory

Magically, overnight, my site returned to normal. Thanks, guppydas, for advice. Unfortunately, perhaps because of my host, I cannot even see the wp-content folders. But I shall see about learning more right away!