Headphone/Speakers problem, HELP?

Okay , so the speakers on my computer USED to work. I could listen to anything , I could plug in my headphones without a problem. Then all of a sudden , the speakers stopped working , AND when I plugged in the headphones, they stopped working too. My daughter does alot of crap on the computer , shes pretty much the only one that uses it! You know FB, Myspace,Twitter, she downloads music and a bunch of stuff. So we soon enough throw away the speakers and for awhile we have a computer with no sound. Whenever relatives have given us speakers that they dont use she tries to plug them in and they still dont work! NOTHING. Its like they were never plugged in. It always says NO SOUND DETECTED. On anything really /: So now , im asking , do we have to buy computer speakers from the store and Install them into the computer & plug the actual speakers in, in order for us to have sound? We tried the whole : RIGHT CLICK MANAGE REINSTALL SOUND DRIVES , but when we do it says that we need to plug in a CD , but since we dont have a CD it doesnt work /: I just need answers ASAP , Person with the best answer gets pointss!! THANKS (: