Assential Game Asset

"An essential game asset was not found when loading the game:

TT_OrderTurret4

Please try reinstalling the game. A guide to help you reinstall should open automatically after closing this window. Or, please visit support.riotgames.com for additional help."

So I'm getting that little error. I don't know why it is, because I just played a game on Howling Abyss and nothing was wrong with it. Though it could just be Twisted Treeline because I am having that issue when I'm trying to play on Twisted Treeline. So are there any solutions? I would like an answer soon.