in my game, i am using two scenes, one for menu and other for game play.
But my game is mobile game so i dont want to use more loads. so what can i do to complete game in one scene instead of using two??
I have no idea why would you want that “because of mobile”, but anyway - just do it in a single scene. Get 1 camera to see only your things you need for menu and the other one to see only things you need for game, and that’s pretty much it, just don’t use some colliders, etc. in your “menu objects”, unless you separate them from “game objects” with “time and space”.
P.S. Obviously you can also go by instantiating and deleting prefabs way if you’d like so.
P.P.S. Also if the main part wasn’t obvious enough - when you’ve correctly setup all your cameras just switch between them on some button click or whatever switches between menu and game and pause all game-related stuff while you’re in menu, etc. etc. (the rest pretty much depends on how your game works).