but i dont know any programming language
Learn one quick, start with Python if you want a easy one. All artist in the gaming industry is expected to understand the principals of programming, so that you can explain to the programmer how to implement your art.
Because making art for a game, is making the art work with the game. It isn't like just making it and it's dropped into the game "working". It's exactly this kind of thinking that makes asset stores a bad idea, lot's of developers think art can just be dragged and dropped into a game.
As a artist in the industry you are expected to be able to implement your work. With Unreal's Blueprint system it's no longer a fact that you need to know a language, however to use the Blueprints you need a basic understanding of programming.
i am not asking which is the best gaming engine i just want an engine that could do landscape designs with good quality mostly focus on 3d stuff and make games like (RPG)
Unreal 4 is the best to start with for you, it or Lumberyard as both are made for fantastic landscapes. Unreal is easier to use.
my experience i do modeling and rigging and animation software's i use are cinema 4d
As a motion designer Cinema 4D will fly, however when you do get employed you will be using other software. Learning 3DS Max is your best chance of getting hired, you can download and use it for free under the student license.
Last pieces of advice: If you don't have a degree it's going to be hard, it's going to be hard even with one. Build a portfolio as soon as you can, you need it more than any thing as a artist.
Remember not to waste time, while job hunting do some freelance work or learn other art related skills, any thing that you can add to your portfolio will make things easier.