Sometimes, when you upload images into your Image Manager, they appear sideways, even though they looked correct before you uploaded them.
Long story short: Re-saving the photo in Photoshop or re-exporting it from Lightroom should fix the problem.
The most likely cause of this issue is that your device wrote the rotation into the EXIF data but didn't actually rotate the file as it should. When software such as Photoshop, Lightroom, Bridge, etc., read the EXIF, they recognize that they need to rotate the image before displaying it. Unfortunately, web browsers cannot read this and will display the photo without understanding it must be rotated.