If you are using VS Community as your game source code editor, then simply
- open .sln, it opens in VS Community, right click on your game name, click build, Done.
Now your project will open.
If you are using VS Code as your code editor,
Then, open UE4, set VS Community as your Source code editor in Editor Preferences, then, right click on your game .uproject file, Click on Generate Source files, then simply do above 1)