We provide a django sample project with our stack but it's not really needed for the stack to work. If you removed the sample project on purpose (This is, you don't have a folder called Project at /opt/bitnami/apps/django/django_projects) and you don't want to have it, you just have to delete the line
And then you should be able to restart your apache server.
On the other hand, if you removed accidentally some files I think the best option is to install a new django stack.
Finally I leave you a link to our wiki that you might find useful:
Let me know if any of this fits your problem