I'm not sure how else to explain this other than saying my rig is not working.

I used the Human IK setup, and created the control rig, etc. etc. It is skinned properly.

My first try was unsuccessful, as using the controls was not moving the mesh (again, not sure how to explain that too clearly). So I asked a friend who is more experienced than me for assistance, and he was unsure of what was going on. So he deleted that setup and created a new one, exactly how I had done it before. It worked, so that was all good. However, when I loaded the file this morning, it is not working again, in the same way it was when I first attempted to rig it.

I'm not really too sure what to do. I could redo it, but then what if it breaks again, will I have to just redo the rig every single time? Have I missed a step/done something wrong?

Any help is much appreciated! And thank you in advance