Make rigidbody character stay on ground

The rigidbody character I’m using for my game will lift off ground and be unable to jump after running up a slope or hitting a bump. Any tips on how I might make the character stick to the ground untill he’s hit by a physics object, jumping, or running off the edge of a platform? I know some C# programming.
I’m using this kit: Advanced 2.5D platformer kit | Templates | Unity Asset Store

hi i suggest you go here

and Here

and also make sure to attach this code to your script

//ommitte using unity...
//this script should be attached to body having rigidbody

public class GravityTest : MonoBehaviour {
   void Start(){
rigidbody.useGravity = true;
}
}

For now, I’ve made it so my character can jump even if he is slightly above ground, which, along with less abrupt angles to run over in my 3D models, has almost completely eliminated the problem.
I suppose gravity isn’t high enough, but there’s so much in the game that relies on the current gravity. Besides, the jumping looks good, so I don’t know how much higher I could go on gravity.

A better solution would probably be to use a character controller when the character is on ground, and use physics/rigidbody when he’s airborne, but it’s a bit complicated for me so I’m not gonna go there.