If you downloaded through Ignite the installation will be in the following folder.
Open up this folder, C:\ProgramData\Aeria Games\Ignite\Downloads\sb
Make sure your anti-virus is disabled
Right click the scarletblade_us_installer_20130306.exe and Run As Administrator.
If it doesn't work check to see if the game is actually installed, default location is C:\AeriaGames\ScarletBlade. If the game is installed try using the SBLauncher.exe to run the game. If the installation folder is empty I would suggest trying to redownload with your anti-virus off as it may have corrupted the installer.