im making an android app and i would like to make the platform rotate (In a 3d way) the way the tablet/phone is rotated
and i want to make a ball go in a random direction and you have to rotate the platform to keep the ball on the platform?
can anyone help me thanks 
This is not the best answer you will receive because I am more a Game Developer from Unity than Unreal (I am totally new on Unreal), but if you want to use random direction, i suggest you to read this page:
https://docs.unrealengine.com/latest/INT/Engine/Blueprints/UserGuide/RandomStreams/index.html
So you will learn to use a RandomStreams.
After, you can create a variable named “direction” from an enum or int and with four constants (NORTH, SOUTH, WEST and EAST) and random a number between 1 to 4, so if it’s 1, you get NORTH, 2 you got SOUTH, etc.
I hope someoneelse will give you a better answer. Good luck