I use project in my computer not in Gdevelop cloud. But today, I have error: Unable to open the project.
Check that file exists, that this file is a proper game created with Gdevelop and that you have the authorizations to open it. I built this project over a week
I create a project saved in my computer but when I open Gdevelop, I have this error ( I don’t use autosave in my project, I usually build manually)
Please help me
Hi and welcome here 
If your project fails to load, there should be an autosave file in the same folder that you can use to open your project.
If you disabled the autosave, well, I hope for you that you made frequent backups, because there’s not much else we can do. 
How I can open file .autosave
In your file explorer, right-click and Rename to remove “.autosave”.