I have looked every where to find out how a laptop screen can flip sideways.
As over 30 years of working with laptops I did not know.
Well there is a solution and I have tried it on my laptop running windows 10.
I originally thought you may have meant your hinges went bad sorry friend
Here is the information cut and pasted.
From some one called cvlong821 thank you dude this works.
Typically, you would use ctrl+alt+up arrow key to flip the screen right side up.
ctrl+alt+right arrow = flip to the right
ctrl+alt+left arrow = flip to the left
ctrl+alt+down arrow = flip upside down)
If that doesn't work, or if your keyboard shortcuts have been disabled, right click on the desktop background, click on Graphics Options, then Rotation, then Rotate to Normal.
Also, if you have Intel Graphics installed on you computer, the software might have reset the default rotation setting. To fix this, right click on the desktop, then click on Graphics Properties. This should bring up the Intel Graphics window. Choose Advanced Mode, and click OK. Find the rotation settings (right side, 2nd from bottom), and choose Rotate to Normal.