Problem with armatures

i am currently taking a course in 3D modeling and have been trying to animate a simple model i made. however when i saved my work than came back at a later time and tested the keyframing the bones moved independently of the model,
and when i check to make sure my vertex groups were still there they were completely fine. does anyone know whats going on?

supplying a blend that shows the problem would get this solved quickly. also, what is your blender version? how is your scene setup?

i am currently using version 2.78
please clarify what you mean by “how is my scene set up”
for example see file attached evolutions greatest mistake.blend (2.8 MB)
please keep in mind that i started this course about a week
ago and as such my work cannot be described of as “quality”