I have read a lot of solutions on this matter. It is as simple as clicking a mouse button to fix. There are two or one white space at the beginning of .htaccess.

Besides, if you look at the bottom of the file when opened you have </ifmodule> whereas there is no <ifmodule> at the beginning. Copy this few lines and replace it with the one you have.

<IfModule mod_rewrite.c>

RewriteEngine On
RewriteBase /

RewriteRule ^articles/{0,1}$ articles.php [QSA,L]
RewriteRule see more ^articles/entry/([^/.]+)/{0,1}$ articles.php?action=viewarticle&articleUri=$1 [QSA,L]
RewriteRule ^articles/entry/{0,1}$ articles.php?action=viewarticle&articleUri=$1 [QSA,L]
RewriteRule ^articles/category/([^/.]+)/{0,1}$ articles.php?action=viewcategory&articleCatUri=$1 [QSA,L]

Hope this will help a lot of people.