The short answer is that you almost certainly took the photo with an Apple iPhone which adds a code to the image to show orientation which is fine when used on an iPhone, but not when you use them on a web site like Beoworld.
One option is to use an iPhone App such as “Camera+ Legacy” and if you think I will just do a screen shot or Photo Viewer that will not help you because the code is embedded within the image.
Beoworld member Dimitris has this problem with his Avatar, his dog is rotated by 90 degrees. The best way for him to fix this problem is to view the image in his phone then rotate the phone and save the image. Take the new saved image with a different file name and upload it to his profile.