my player keeps falling through everything terrain and shapes

Does your player have a collission mesh? If you added a character motor to it, make sure that the green pill-shaped thing is above ground. you could try moving your player upwards, i think your collission might be "inside" the terrain, and therefore falls through instead of popping up.

i cant find where to add collission mesh and i tried putting him above the terrain but no matter how high i put him the player always falls through the terrain

Perhaps you set the terrain collider to "Is Trigger" if its set to true, make it false.

i set it to false and my player still fell through the terrain and its not just the terrain my players falls through everything also if my player doesnt fall through the terrain the player doesnt move

Though I am bit late but for people facing this problem at this moment. Try Enabling isKinematic inside your Player's RigidBody Component. This one solved my problem. Enable Gravity and isKinematic, that was the solution for me. And Disable isTrigger inside the collider.