Python Error: No module named adminsortable2.management.commands.reorder
This is probably because you don't have package django_admin_sortable2 installed.
You can install it in command line via pip:
pip install django_admin_sortable2
Install specific version:
pip install "django_admin_sortable2==0.7.6"
Get more info about package via pypi.org: django_admin_sortable2