[GAMEPLAY] Xerath Q stopped working

I was playing a ranked solo q game on xerath, then out of no where i started lagging, i check my internet and it was not me it was the game. Once i stopped lagging i got into a team fight and when i press Q, the skill loaded, kept on powering up, and then disappeared and never came back. When ever i pressed Q after that nothing happened, i even let myself die to see if that will fix the problem and it did not. I was so frustrated because i was pretty much the carry and i couldnt use one of my strong skills for late game.