topsoft hack

I have a site that has been hacked. It has thousands of pages indexed in google. All with topsoft in the url, its structured domain.com/topsoft/some-product sell. When I do a google search for “topsoft hack” I can only find other sites that have hacked.

I dont see any files called topsoft in the main directory of the site. I didnt see anything wrong with .htaccess file. Has any else had this hack? and how do I fix it?