Can somebody help me i want some kind of script where camera follows ball (and game is based on roll a ball) ,Can anybody help me with camera follow i want script with only camera following i created roll a ball based game and i want someway camera can follow ball.
If you want the camera to follow your ball, you can simply make your camera a child of the ball in the hierarchy.
If you’re wanting to add smoothing, etc then you’ll need to write a script.
You’ll want to Vector3.Lerp from the current camera position to a target position.
Your target position will likely be the balls position + an offset to make sure the camera is consistently viewing the ball.
I’d recommend checking youtube for some tutorials. 
This is one of the first things people learn, props on coming to the right place for answers, but you’ve got free solutions on youtube that you can learn from at your fingertips.