Sometimes digital photos auto-rotate when viewed in various software programs, and this can be annoying. How do you stop the auto-rotation??? See answer below.
First, learn WHY it is happening...
Digital image auto-rotation happens when the images have extra EXIF metadata stored which defines the image's orientation. This EXIF info is often written to the images when photos are taken with devices such as smartphones, tablets, and some digital cameras. The auto-rotation happens when the software used to view the images cannot read the EXIF metadata or reads the EXIF metadata incorrectly.
Solve the problem...
Simply remove the EXIF metadata from the digital images. If you use Windows, the steps to removing the EXIF metadata are--
1. In Windows Explorer (the window with the folder and file icons) right-click on the image file that is auto-rotating;
2. From the pop-up window, select "Properties";
3. In the Properties dialog, select the "Details" tab to view the EXIF metadata;
4. At the bottom of the Details tab, click the blue-underlined text that says "Remove Properties and Personal Information";
5. In the Remove Properties dialog box that pops up, select the radio button that says "Remove the following properties from this file" to enable selection of properties in the list;
6. You can then click/select each piece of EXIF info to remove, or use the button at the bottom to "Select All". Personally, I always use the "Select All" button because I never have found EXIF info to be useful to me.
7. Once the EXIF metadata to be removed has been selected, click the "OK" button, then click the "OK" button in the Properties dialog.
That's It!
Another way to solve the problem...
EXIF metadata is not saved in image files with the PNG file format which, in my opinion, is better for preserving digital images against JPEG artifacts and other problems that often creep into JPG files. If you have software that can convert image formats then by converting the images from JPG to PNG will effectively strip the EXIF metadata from those image files.
If you have a lot of images you need to convert to PNG file format, there are some free batch converters that you can download and try. If you have image editing software, some image editing software allows batch conversions of image filetypes so that is another option.
Keep the problem from happening again...
If the images that were auto-rotating were taken with your smartphone or other device, consider turning off the camera settings that are writing EXIF metadata to your images. Not only will you be resolving the problem for yourself, but you will also keep from causing problems for others that you share your images with.
IMPORTANT NOTE
After removing the image's EXIF metadata, the images may appear rotated when viewed on your computer. If this happens, it is because the image was saved in the wrong orientation and the EXIF metadata was making it appear to be in the correct orientation. If this happens, you will need to change the image orientation using image editing software or an image viewer which can rotate images without using EXIF.
I found a utility that claims to do batch EXIF removal from digital images. I have not yet downloaded and tested the utility, but I have read a few reviews and the software does look promising. It is a Freeware utility called EXIF Purge - there is a version for Windows and for Mac.
I repeat... I have not tested it yet, so I don't know how good it works. The reviews say it is good, though. Before using it on important image files, I highly recommend testing it on image files in a different folder - and always be certain to backup your files before trying to modify them with software you are not familiar with.
The EXIF Purge utility is located here...
https://www.exifpurge.com/