Fill in the gaps with could, couldn't or was able to.

I was walking in the woods one evening when something terrible happened. I slipped and fell down a hill into a stream. It was quite dark and I 1) ...couldn't... see very well. I called for help but no one 2) hear me. I had hurt my ankle and I 3) walk very easily, but I tried. After some time, I 4) ..... start going up the hill again. It was late and I was cold and wet. I wanted to go home, but it was too far to walk. It took me a long time, but eventually I reached the edge of the woods There was a house there, so 15) ..... my father. He came in the car and took me home. The following day, the doctor came and examined my ankle. I had to stay in bed for two days. It was a week before 16 ) walk properly again. ​