help me help my brother

Im currently in work, but my brother is having problems authenticating his game. He tried through steam and it worked, then he had to turn his pc off while he went to the dentist. Hes come back and its tried to get him to authenticate again and then said hes already done it but he cannot do anything with the game. Hes since uninstalled and tried to do it again with the other option and it now says as hes already authenticated he has to buy another code!!!!!!!

What is going on with this......ive not even tried my copy....but hes been home all day and its now 430pm and he still cannot play this game. If it was me i would not be happy at having wasted my entire day off work!