Restart your PC Open League of Legends again This should fix the problems you've been having as it will force LoL to reinstall Vanguard correctly, with the file paths in the right places.

The Vanguard Error VAN 57 in League of Legends occurs when Riot’s anti-cheat engine, Riot Vanguard, fails to start correctly.

League of Legends cheaters' jobs just got a little harder thanks to a new form of anti-cheat system coming to the game. The kernal anti-cheat advancement, developer Riot says, is designed toward ...

Riot Games addresses rumors claiming League of Legends' implementation of its custom anti-cheat software, Vanguard, is bricking players' PCs.