You have not created any content types yet. Go to the content type creation page to add a new content type.

I am working with a drupal site when I noticed that clicking "Add Content"  does not display the existing content types.

Here's the error. It appears when I click the Add Content link.

           You have not created any content types yet. Go to the content type creation page to add a new content type.

Searching the net points me to forums suggesting that I enable all the content types under Add Content at the NAVIGATION menu. These steps had solve most of the askers problem but not mine. :(

Also, I noticed that I actually have 2 "Add Content" links at the Navigation menu. Where does that came from? I don't know!  I don't remember creating a new Add Content link but its there. 

And then I try moving my existing links under Add Content (number 2)  to Add Content (number 1) link.  Wow it worked!!

My content types are available again. 

I dont really know what happened and cannot find explanations about it either (I did search of course).  But that's the least of my worry right now. I'm so glad it is now resolved. I can't afford restoring the site from backup since I've done a lot of updates today...

Note:   If your case is different from mine, try visiting these links:  SOLUTION 1,  SOLUTION 3 ,  SOLUTION 2