Pc is telling i have no sound card

Hello, my pc crashed on me and i was able to bring it back to life (some what) but now its telling me that i have no sound card, and im unable to use my go back to restore it, i dont even know what the sound card looks like to try to re install it or what it is called, a friend bulit my pc from scrach, so i have no idea where to start.... please help someone