Image error

My imageuploading has stoped working. When I upload an image I don’t get any errormessage but the image won’t display, I only see the name of the file. The same happens when I then sends it to the edditor and publishes the post. I have tried with multiple images some who I have uploaded before without any problems so I know it’s nothing wrong with the image. If I use ftp I can se that the image has been uploaded and if I download it from the ftp it displays fine on my computer. But as I said I can’t se it in wordpress after uploadning it and if I tries to surf directly to the image I get a wordpress error 404 – file not found.