Patcher Stuck at 33%

https://support.riotgames.com/hc/en-us/articles/201752664-Troubleshooting-Connection-Issues

Try the things they recommend in this thread. I've tried them personally and they did not work; however, some people are saying it has for them. This has been an issue for about 16 hours or so now. Riot has not commented on it either. Best of luck.

~ Jarod

As long as it's still scanning files, just let it run, and ignore the percentage, it will finish somewhere after about 3000 files. Takes maybe 20 minutes.