Are you sure "VALORANT" is the right title ?
Have you checked if hwnd is not null ?
A test with Notepad shows it works :
// Class = "Notepad"
IntPtr hWnd = FindWindow("Notepad", null);
if (hWnd != IntPtr.Zero)
{
SwitchToThisWindow(hWnd, true);
SendKeys.SendWait("+{ENTER}iyi oyunlar...{ENTER}");
}
with :
[DllImport("User32.dll", SetLastError = true)]
public static extern bool SwitchToThisWindow(IntPtr hWnd, bool fAltTab);