htaccess assistance please

If I have people trying to visit www.blah.com/abc/123.html and the abc/123.html is now gone for good and its just the domain itself what can I add in the htaccess file so tell the search engines to stop looking for those files.
There are hundreds of e.g. abc/*.html files indexed in search engines of mine and when a user clicks on them I want them redirected to the main domain, how is this achieved?
Thank you.
Answer #1

There are hundreds of e.g. abc/*.html files indexed in search engines of mine and when a user clicks on them I want them redirected to the main domain, how is this achieved?
Create a 404 redirect to your homepage.
http://www.htaccessbasics.com/404-custom-error-page/
can’t help about other question.