Riot Games forgot to include a Windows dynamic link library (DLL) that is required to run the game. Windows users are reporting that they are unable to launch the game and are shown either a ‘VCRUNTIME140.DLL is missing’ or ‘V CRUNTIME 140.dll is missing. A later patch released tonight by Riot Games alerts users who start Valorant that they need to install the “Microsoft Visual C++ 2015 Runtime”” Users who have installed the runtimes in the past will not need to do so again.”
Source: https://www.bleepingcomputer.com/news/microsoft/valorant-update-causes-vcruntime140dll-is-missing-error-how-to-fix/