No Sound on my mother's laptop.

I am trying to figure out what happened to the sound on my mother's laptop. I just got it back for her from being repaired. It had sound before the repair and now it doesn't. I've checked all the basic things I know how to check and we cannot afford to take it back to the repair man...he already got enough money out of us LOL! If anyone can tell me where to start I really need some step by step help in checking for problems.