Example of deleting a cached KVStore instance that sorl.thumbnail thumbnail templatetag creates. Pretty edge, but handy when thumbnails aren't being generated for whatever reason.

invalidte_thumb.py

from sorl.thumbnail import default
from myapp.models import MyModel

# Get an model instance that has a File/ImageField associated with it. In this
# case the `thumb` attribute is an ImageField that we'd like to generate thumbnails for.
m = MyModel.objects.get(pk=10)

# Note the options passed to this method -- they are applied to the cache key so 
# the ImageFile instance that is returned will be different for a different set
# of options kwargs provided here. In this case, the only option is `upscale=False`.
thumb = default.backend.get_thumbnail(m.thumb, "300", upscale=False)

# By default, thumbnails will be deleted along with the KVStore record.
default.kvstore.delete(thumb)