First of all, please check and make sure they are supported files (jpeg, png, or gif).
Second, we have a file size limit of 8MB and an image size limit of 1200 pixels wide.
Anything larger than these two size limits can affect whether or not a file can be uploaded. For example, professional photographers will often give images that are 2000+ pixels by 3000+ pixels in size. These are very high-quality and high-resolution images that can be printed as sizable enlargements, which is great to have if you ever want to have an image printed, however, they are much too large for the web.
If you have a PC, check the image in Windows Media Viewer or Microsoft Paint; if you’re on a Mac, look at it in Preview to check the size of the image, and you can resize it there as well; 1200x2400 pixels will be more than large enough to have high-quality web viewing.
If none of these approaches work, go ahead and attach the image to your helpdesk ticket and we will investigate.