@johnbishop I saw a video where they laid on a bed a walked their legs up the wall by the headboard.

Chris, try laying in a doorway with your legs against the right door facing. The door facing should be at about your waist. Bring you knees up until you feet are flat on the floor, then bring the right knee to your chest, which you can assist with your hands or a strap and place it just inside the door facing on the wall. Once you have the right leg in place on the wall you can pivot your body to the right with leverage from that leg allowing you to bring the left leg up the same way. At that time both feet will be on the wall and you can comfortably slide them upward into the vertical 90 degree position. If flexibility prevents this maneuver then an alternative is to lay at the foot of a chair or sofa and bring your feet up on to the the sitting surface. This will place your thighs in the 90 degree position. You can place straps around your ankles that are long enough for you to be able to pull your lower leg into the full 90 degree position. You may have to do one leg at a time. If you can't reach the feet to do the "milking" maneuver the wiggling and flexing and extending of the feet and ankles should help a great deal. If this doesn't work then John's headboard suggestion may be the answer.

@rramsey Try placing a bolster or a sturdy pillow against the wall, then gradually roll your butt up on to the pillow, while slowly sliding your legs up the wall. Good luck!