I have a little problem that I will love you to help me out with, 4 months ago I went for a competition but during my fight I got injured (Knee) and since then it has been affecting me. I really love TKD and I'm finding it very difficult to stop training and even sparring but I need you to tell me some of the best techniques to use so that I won't expose my knee to further injury.
First, seek medical attention and follow the doctor's recommendations. Most doctors will tell you to let the injury rest so it will heal. This is always difficult to do, but it works. If you don't let it heal, it will just be a constant problem that may never go away. As to exercises, the knee will tell you what not to do. If something cause the knee pain, don't do it. If something doesn't cause pain, then keep doing it.
There are so many things to learn in the martial arts, other than sparring, that you may train on while the knee heals.
Weight training is always productive. A trainer at the gym will show you exercises to strengthen the knee.