Unable to use spells in game. (Help me please!)

Occasionally when I get into a game my keyboard isn't working. I can use the esc key and type in chat just fine. But I am unable to use spells or hotkeys. I typically have to close league and reconnect, sometimes I have to close the client and reopen it to make it work. I used to have this problem several months ago and it magically went away. Now it is back. Any that has an idea for a fix please let me know! Thanks!