404 Not found fixing for changing permalink status

Question

In very beginning I used wordpress permalink setting like below.

http://www.example.org/sample-post/

After adding 20 articles I have changed permalink custom setting like "/%postname%.html". This is why 20 articles are showing 404 not found. In these circumstances, what can I do to solving the 404 not found error? Please assist me..

Answer 1

Try flushing you rewrite rules.

use this plugin

then in tools hit 'flush rules'