How to run previously created Django Project
Simply navigate to the folder containing the app you want to manage using the command prompt.
The first cd should contain your parent folder.
The second cd should contain the folder that has your current project.
The third cd should be the specific app you want to work on.
After that, you can use the python manage.py to keep working on your app.
I am new to Django. I am using Python 3.7 with Django 2.2.6.
My Django development environment is as the below.

I am using Microsoft Visual Studio Code on a Windows 8.1 computer
To give the commands I am using 'DOS Command Prompt' & 'Terminal window' in 
VS Code.
Created a virtual environment named myDjango
Created a project in the virtual environment named firstProject
Created an app named firstApp.

At the first time I could run the project using >python manage.py runserver
Then I had to restart my computer.

I was able to go inside the previously created virtual environment using
workon myDjango command.

But my problem is I don't know how to go inside the previously created project 'firstProject' and app 'firstApp' using the 'Command prompt' or using the 'VSCode Terminal window'
Thanks and regards,
Chiranthaka