On your PC, flip it 360° and save it again under a new name. Your OS uses different image orientation information than browsers do. This way you can overwrite it.
I meant what I said. it "looks" like before, but when you save it, you'll overwrite the orientation info that the browser is reading with the the ones the OS is reading.
I know what you mean and I'm probably explaining it poorly.
You open the image on your pc, with windows photo viewer or whatever. No need for Photoshop.
The image will show up correctly. But if you upload it in your browser it's upside down.
In the photo viewer you rotate it four times, in a full circle. Then you save it under a new name. When you now upload the new image, it's up right.
I have dealt with this issue countless times while working in tech support for years. And that was the solution that helped every single time.