Cannot Use Certain Skills

I just played a game as kat. At around 10-15 minutes, i was not able to use the abilities Q,R, and the Port back to back. Also, i have tries to use the abilities from the screen itself, however, that did not work either. I tried to set all my key bindings to default, however, that did not work either. At around the 35 minute mark, I would seem the my abilities have worked again. If anyone knows how to fix this problem, please respond. Although it has not occurred in the past few games, I fear of the possibility that it might happen again. Please Help Me!