You took a video with your phone but it’s upside down? There are several mobile and desktop apps but it’s tricky to find one that is easy to use and free of charge.
I came across an app called Movie Maker. It gets the job done easily. You can rotate videos 90 degrees at a time.
Here is how to rotate a video in seconds:
Download at Microsoft Store: www.microsoft.com/en-us/store/p/movie-maker-free/9mvfq4lmz6c9