My father has had a tough last 6 months regarding falls. He has had 9 of them! I have to help him up, and it takes me up to an hour to get him on his feet again. First, I have to help him get to a sitting position on the floor, which he can't do without my help. That takes a while, believe it or not. Then, I wedge one book under his left bum cheek, ask him to roll to the left, stick another under the right cheek, roll to the right, and so on. Building up this way is the only method I found that works! Can be a bit unstable but has worked so far. When he gets to a sitting position, I can then lift him up to standing position, then lifting from under his arms while he pushes with his feet.
Before going into hospital, he had 3 falls in 2 days. First one, I was in bed and heard him calling out for help. I lept out of bed, got there and he just started to fall and I caught him in time to break the fall. Had to call ambulance to get him to his feet because I currently have a bad back myself and so can't do heavy lifting.
Next he was coming back from the toilet with the zimmer, and I heard him calling out again, he said he was about to collapse, so ran downstairs and held him under his left arm, to help him to his chair. Then the last one, where he fell while washing his hands in the toilet. Had to call the ambulance, and they took him to hospital.