Images not uploading in WordPress 3.5, gives an error but visible on the server

It is weird. I try to upload and add images to a post via the media uploader, but it gives me a try again later error. No images are shown in the media library either. But when I check the wp-content>uploads folder on the server, it is uploaded to there with the small and medium sizes too. I can add images by getting the URL and so on, but my site runs on featured images, so I need to get a fix to this.

And before you guys go on for the WordPress master trouble shooting list, I must tell that I de-activated all plugins and tried, did not work. Switched to twenty twelve theme, did not work. I have also tried numerous other solutions found on the net and on this site too but nothing seems to work. Please help me asap.

My site is OnlyRihanna.Com