It depends on your age but I hope you can understand what I am going to tell you. When you have a bad fall or injury your brain makes a connection between that skill and pain dependent upon how out of control you felt and how much emotion the incident created. If you were embarrassed or sad because you didn't get the score you wanted or do as well as you know you can, that could factor in. Your brain has made a path and sometimes it can be an actual crease and you will have to reroute your thinking. If you want to do the trick, first you have to honestly determine if:
1. You have the ability to complete the skill
2. You know, you know how to complete the skill and
3. You know you have the strength and flexibility to do it.
4. You will have some pain after an injury and you have to be okay with that.
If you meet those criteria then you have to now deal with your brain. You can trick your brain by adding another stimulus, You could do something as easy as sing "baby sharks" when you do the skill or you could use aromatherapy and take a whiff of lavender or peppermint before you start. Smell is one of the greatest senses
Sometimes someone saying "1,2,3 go" is helpful but the truth is it really works best when you say it yourself. Don't keep your hands over your head before you go, or get in the position to do the skill, that only reinforces that it isn't happening. Just stand straight and when you are ready then put your hands up and go. Write down what you want to do each gym session and how many reps of whatever, then mark off as you complete your goals. This way the skill is being handled with logic and a plan instead of feelings.
I wish you the best of luck.