Lost sound on my Inspiron 531 PC

I brought my PC into the College that I am attending because it was running extremely slow. They burned everything to CD's and reloaded my software; now I do not have sound, not even when I turn on my PC. I have checked to make sure nothing was muted, speakers were plugged in correctly, ran Microsoft driver and sound check to confirm that my Realtek High Definition Audio software was working properly. No one is available to look at it until fall classes resume - does anyone have any suggestions?