The current version of WordPress does not provide a mechanism for retrieving comments accidentally marked as spam. This can be circumvented with the Akismet plugin.

Akismet is a WordPress plugin that evaluates and deals with regular spam comments as well as trackback spam.

If a comment matches up with spam in their database, Akismet dispatches it swiftly, saving you the hassle of moderating several spam comments on a daily basis.

As an added bonus, Akismet allows you to view caught (or marked) spam and retrieve it from the database.

Step-by-step instructions for recovering a comment accidentally marked as spam in WordPress:

Step 1. Install the Akismet plugin.

Akismet is included in the core WordPress distribution. It can also be downloaded from the Akismet website as a zip file.

If Akismet is not already in the plugins list, then:

1. Download the plugin.
2. Extract the zip file into the wp-content/plugins folder in the hosting area for the WordPress website. This will create a new folder called “akismet” in the plugins folder.
   

Step 2. Activate the Akismet plugin.

1. In the main WordPress dashboard, click Plugins in the top right corner to access the Plugin Panel. Akismet will now be in the list of inactive plugins.
2. Select Akismet and click Activate.

Note: Akismet activation requires a WordPress API key. If you have a WordPress.com account, you will find the API key in your profile page at WordPress.com, or in the e-mail you received from WordPress.com to acknowledge user registration.

Step 3. Find the comment that was accidentally marked as spam and retrieve it.

1. Click Comments at the top of the WordPress dashboard.
2. Click Akismet Spam to access the “Caught Spam” panel.
3. Find the comment to be retrieved and tick the “Not Spam” checkbox underneath it.
4. Scroll to the bottom of the screen and click De-spam marked comments. The comment will reappear in the “Manage Comments” panel.