Don't be disheartened. Maybe do another flight with your instructor to rebuild your confidence and then retake your test. Almost everyone has a day or an experience which leads you into thinking that you just cant do it during your PPL.
Mine was making a right hash of an approach and landing on my first solo cross country - almost didnt get back in the plane to take it back to base. Took a deep breath and flew back and talked it all through with my instructor. Next day did my qualifying cross country - all 3 landings were still about the best I have done to date.
So the chances are if you retook your test the tomorrow you would breeze it. So chin up, take a deep breath, you would not have been put up for your test if you were not ready, and go show what you can do.