Yesterday I was working with my laptop connected with a remote monitor. I realised the screen in my laptop looks upside down. Not sure I did pressed any key combination or a bug with windows. Searched for the screen turning around and found this good tip. This is with windows 10. May work for other versions also.
Tips for turning the screen around:
If you want to turn the screen upside down, press “Ctrl + Alt + down arrow”.
To turn the screen back to the default position, press “Ctrl + Alt + up arrow”.
To turn the screen on to the side, press “Ctrl + Alt + left/right arrow”.