Wordpress - Wordpress plugin shortcode not working
There are a couple of things to check here
One: Is your plugin activated.
Two: Is your shortcode in your main plugin file. If that code is in another file inside your plugin, did you make sure to include that extra file into your main plugin file
Three: Don't you have any type of error in your plugin file that deactivates your plugin after activation. Have you set debug to true. One of the site's members have an excellent debugging plugin available for download on wordpress.org called Debug Objects
Four: Try moving your shortcode to your theme's functions.php to make sure that your shortcode is actually working. If it doesn't work inside your theme, the problem might actually be in your theme itself
Five: As suggested by @helgatheviking, aren't you filtering the
the_content()in any way that might cause this behaviorSix: If all of the above fails, deactivate all plugins, switch to a bundled theme, and recheck. If the problem persist, upgrade/reinstall Wordpress, as this might be a corrupted core file then