Help me restor my sound

Two days ago, I installed Dragon Naturally Speaking 10. I used a pair of headphones with microphone that I had, so that I could test the software out. I plugged in the headphones on the jack in front of my laptop. All of a sudden yesterday I turned on my laptop and there is no sound from the speakers. I have tried everything I could, even deleted the sound drivers and installed them again, but I still get nothing. I am running Windows 7 Ultimate. I have read on other websites that Windows 7 is a little funny when it comes to the sound. I have a Dell Inspiron 1420 laptop.
this question is the same my problem. pls. send me reply