Valorant may not load or launch due to various reasons. Some possible solutions are :
Restart your computer and Valorant.
Check your computer specs and resolution.
Update your graphics driver and Windows.
Run Valorant in compatible mode and as Administrator.
Close all Riot related processes and other applications or games.
Temporarily disable your antivirus and stop overclocking.
Delete and reinstall Vanguard and Valorant.
Log off your account from another device