League Launcher doesn't start with the new Patch

Hey guys,

starting yesterday, my Launcher just doesn't start. I launched it as admin, re-installed League completely, used the Hextech Repair Tool to force it to patch again and tried most of the other tips you can find online, but nothing works.

As soon as I am starting League, I am just stuck with the logo in the middle of the screen while it's loading the Launcher (without any progess bar though). The Launcher never pops up, I am just stuck there for hours.

Any idea how to fix this?