My Games Aren't Working!?

OK hay i figured out that my brother did something to them also i figured out the it has to do with the sound i have a vista computer neither Guild Wars Nor World Of Warcraft Work on my computer he did something to the sound to you can still hear everything on the speakers nothings wrong with that but when you look at the volume theres an X by it a red X in a circle i have tried reinstall my games like 50 times but the weird thing is when i try reinstalling them it never finishes like for GW i uninstall it (mannually cuz it wont let me do it on add and remove programs.)by deleteing all the GW files then go to the site and download it and i have tried using their discs also i dont have a virus did 4 different virus scans so its not that my bro told me he did something so could you all help me. I've ask this like 50 time but still nothing! also for WoW i click on the main page icon when i do that the ad comes up saying Play and options and all that then i click on play and the game wont work i was think he blocked the games systems from the computer like Blizzard and Arena Net because for guild war even the arena net loader wont come up no i dont have a probelm with the internet i can play my other games such as Dofus and Runescape. and I can play Full-Screen games too like that one game that comes with it Fate. i did say i have Vista also THIS COMPUTER HAS NO PWORDS on it so its not a pword problem then and i dont have enough to by a new computer and im not going to give him a doughnut and be nice to him... ok. i think i covered everything all i want is a way to fix my PC!!! help O.O