Loading screen going into games just stays on a black screen

So yesterday the 16th i started a game of league and about 5 minutes into the game my game crashes, so i do the obvious thing and try to reconnect. That does not work, so i restart client and still does not work every time i try to reconnect it just sat on a black screen. I then restarted my computer twice and shut down my computer nothing changed. Then i tried repairing the client and still nothing changed but this time i lost my item sets. Now I go to the only option i see left, re-downloading the client. STILL the same problem cant start a game or spectate a game without the screen going black. I use a Mac operating system Mac OS X Yosemite I already tried twice on the forums to get help and have not gotten any, in addition i filled out the form under technical issues to riot's support staff. Please assist me I don't know what is left to try at this point and I DO NOT want to have to quit league because the games wont load, I also do not want o get banned for my game not loading since it is out of my control, so please if anyone especially Riot know how to fix this please tell me.
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