About 4 weeks ago, my little sister was playing game then she saw a box which asked about the sound things. She didn't know anything then she just closed it. After that I could not hear music or any sound from my computer. I tried to install that sound program again but it was no use. Then the next day, when I click to turn on the CPU, the screen said there was NO SIGNAL. After that I can't even use my computer anymore. I thought the problems were sound card and video card but i'm not sure. IF ANYONE KNOW HOW TO FIX IT PLEASE HELP ME. THANKS.

About 4 weeks ago, my little sister was playing game then she saw a box which asked about the sound things. She didn't know anything then she just closed it. After that I could not hear music or any sound from my computer. I tried to install that sound program again but it was no use. Then the next day, when I click to turn on the CPU, the screen said there was NO SIGNAL. After that I can't even use my computer anymore. I thought the problems were sound card and video card but i'm not sure. IF ANYONE KNOW HOW TO FIX IT PLEASE HELP ME. THANKS.

What is your set up? Mac, Windows Vista XP or what. What is connected to it?