No, it is impossible to cause that. Your eye anatomy does not allow the contact lenses to roll to the back of your eye. The inner surface of the eyelids has a thin, moist lining that is called conjunctiva. At the back of the eyelids, the conjunctiva folds back and become the outer covering of the white part of the eyeball. That is to say, There is no opening around the eyes for anything to get back behind them.
Do your mean your contact lenses are not on the right place in your eyes. And you can't find where are the contact lenses go. If so, it is possible happen sometimes. If you meet this situation, you can try to use many eye drops to flush the lenses out. Or you can try another way. You need clean your hands first. Then, put your finger on the area of your lid and feel the contact lenses so as to know where it is located. Then, gently lift your upper eyelid or pull the button eyelid to see if you can visually see the lens. Find it and remove it gently.
The surface of the eyes is a pocket structure, whose interior part is closed and opening is towards outside, so it is not possible for the contact lenses to roll to the back of the eyes. The best explanation for the missing contact lenses is that you have dropped them unconsciously. If you cannot set your mind at ease, go to the hospital for an examination.