Sprite.ResumeAnim() works. If it's an action with no parameters it needs the () so maybe that's what was missing.
For the 2nd edit, you can change the function from
def save(filename, *objtypes):
to
def save(filename, objtypes):
to make it use a list.
Then call the function with:
save("myfile.txt", [sprite,sprite2])
instead of
save("myfile.txt", sprite,sprite2)