This has happened unfortunately several times. Many very good threads have lost the images, especially any inserted into the old forum platform. There was also an issue where some photo hosting sites (possibly yours?) blocked third-party hosting. Examples are Photo bucket and Tiny Pic, which caused very many images to disappear. Perhaps this happened to you which is very unfortunate. I don’t know of any way to fix it, except to upload them again if you wish. Many members here have had the same problem and had to upload images again.
In your case it is a shame, as you have posted so many top quality helmets like the incredible M1856 above. I have never seen one in such condition. A perfect close up of the M1842 Line eagle Wappen that I search for endlessly, and that is very much appreciated.