I have problems with windows vista

Hello,
hi I have a problem with windows vista I got my computer from the store and it came with the windows vista intall It was working nice for a bit but after I starter downloading program to it I have problems with the sound from the computer speaker I have no sound at all so I check the speaker conections and everything was ok I didn't know what was wrong I try system restore and it brought the sound back for awhile so I kept on having the same problem over and over againg and using the system restore to fix it I even try to restore the computer as it came from the factory it work for awhile and now I can't even use systeme restore anymore. now when I turn on the computer it show some message that say some system error are preventing windows vista from booting, since I can't use system restore any more I try to fix it by using the window vista cd It send me to system restore and to intall a fresh windows vista so I try to fix it using system restore first because I didn't want to losse any program I didn't have a back up and system restore didn't work again. so I try to intall a fresh windows vista and now I have a new windows vista intall in my hard drive pluss the windows vista that wouln't boot with errors and I still have no sound in my speakers. my question is if you can help me how do I get the sound back in my speakers and how can i fix or get rid off the windows vista that wont start because of error can any one help me please