Problem with environment in my scene

Hi all!
I add new asset in my scene, i see window with reload,ok i save project and reload.. After reload my scene,all environment just lose, i have only terrain(trees,grass). I save my project over 30x time. I dont know how fix this,i remake my scene second time..and again i have this problem.Help pls

 

Just by looking at your screenshot, I am not sure I understand what is going wrong. Is it possible for you to capture and upload a video or GIF of the problem happening?

One thing to note is that "Save Project" and "Save Scene" are different options in Unity. Open up the File menu in the top left corner and click on Save Scene and see if that saves the changes that you have been losing.

You can always tell if your scene has been properly saved by lookin at the top level scene name in your Hierarchy and looking for the * at the end of the name. Check out my attached screenshot for an example. If you have an asterisk * there, you have unsaved work and you must save the scene before you exit Unity.

One last thing to be careful of -- with Unity, if you make changes to your scene when your game is playing (often referred to as Play Mode), all of those changes will be reset when you exit play mode.

If the above hints don't help you save your scene, then please grab a video of the problem you are having and post it to this thread.