Continuous 404 even after redirection - what to do for mass

Question

My WordPress blog's permalink was /%postname%/, but for some reasons I changed the permalink to /%postid%/%postname%/, and found there was much problem in many other cases, so reverted the permalink to /%postname%/, but within this time, google did what it was made for. And now I'm getting continuous 404 in many ways...

Common are:

• http://example.com/%postid%/%postname%/
• http://example.com/date/%year%/%month%/

So I installed Redirection plugin and using it for many days. I've made redirection for these two cause, but somehow it's not actually working. A new type of 404 is generating like

• http://example.com/%postid%/%postname%/attachment-url

I'm tired redirecting them everyday one-by-one from the above to:

• http://example.com/%postname%/attachment-url

What can I do now?
How can I let google crawler understand that I'm not in that instance, I'm back to my previous option?

Answer 1

Place this rule as your first rule after RewriteBase:

RewriteRule ^[0-9]+/([^/]+/[^/]+/?)$ /$1 [L,R=301,NE]