Am I reading you right: you got a physics B.Sc., but your grades were not good enough to get into graduate school? If that is correct, you'd be surprised: I can barely do anything in physics, but I just breezed through undergraduate computer science. Undergraduate math, astronomy, anything, isn't that hard for me either - physics I find impossible. If my assessment is correct, try taking some courses in a field like computer science or engineering. Then take the GREs and apply to graduate school. From what I've read about how hard physics is, you would probably get in and get through. (E.g., read about physics here:
https://www.reddit.com/r/Physics/com...nted_to_share/)