If you're having a bugsplat

Try the Hextech Repair Tool. Do a clean uninstall and reinstall. This is different from a regular install because it doesn't just remove the game but all of the residual data, so it will be almost like the game was never there in the first place. This tool makes it very easy to do it, as it will also do the reinstalling for you.

I was having a bug splat error every time I tried to get into game. I had tried everything on Riot's page on fixing Bugsplats and nothing worked. I downloaded this tool, did a clean uninstall and reinstall, and it worked like a charm. LoL is actually now running better than it was before.

Idk if it will work for you too, but it's worth a shot.

(P.S. You will have to scroll down the page a bit to get to the download)