I want to know what I can do about a landlord entering my home when I am home and when I am not home.?

Is there a law that protects me from this? Is there something I can do to stop it. I was sleeping one afternoon and got up cause I heard something and when I came around the corner of my living room. i looked up and saw my landlord standing there. Of course I screamed and he said what. I said what are you doing in my house? He said no one answered the door. Is this wrong or what? I was truly feeling violated. Am I wrong or him?