[cericd]

If you open the offending file in MS Paint and rotate it to the correct orientation, even if it looks right when first opening turn it a quarter in either direction then back and save the file, ctrl+S or File / Save. I’ve never had to rename. There are ways to use Windows Explorer to find out which files will show up sideways prior to trying to post them but you’ll have to play with Explorer Folder options to find the folder setting that shows orientation in a column next to the file names.