abilities wont work as katarina

in my last game i played kat and in the middle of the game all of a sudden my q ability and my ultimate were not working when i was trying to use them. i use quick cast and never had problems with it before but when i went to q the minion wave it was not doing anything. it also was not letting me back to base i had to walk all the way back and when i was standing next to an enemy champion my ult would not go off when i would try use it and i was not stunned or anything at the time. this all went on for about 5 minutes during the game until i died and when i revived i was able to use my abilities again.