Why is the_content() not displaying the content? [closed]

in my wordpress site, the_content() is not showing the content, but $post->post_content shows it, why this is happening? and how can I use the_content again?

In order to use “the_content()” it must be used within The Loop.

See here: http://codex.wordpress.org/Function_Reference/the_content

“Displays the contents of the current post. This tag must be within The_Loop.”