(1) Delete Infinity.
(2) Use this tool to delete cache and cookies from Infinity automatically - ICDV2.bat - (use the default option for easy-ness)
You can also do it manually if you find it fancy
(3) Download Infinity from here https://s3.amazonaws.com/wemod/infinity/releases/master/Infinity-Setup.exe (or from here: WeMod | PC Game Cheats, Trainers, and Mods in One App )
(4) Install again.
(5) Enjoy ^^