League Wont Start Up

Hi,

When I open up my league of legends, it will show the logo, and then just disappear. It will not keep running as a background app and I reinstalled and redownloaded it twice already. I also rebooted my PC a bunch of times. I have not been able to find a solution for this, it was running just fine 2 days ago and then suddenly stopped working. Any help would be really appreciated.