I Can't Hear Anything On My Laptop..Help!

The other night I wanted to watch a movie on my Dell laptop without waking anyone and so I plugged in my head phones, when I noticed no sound was coming out of them I took them out and tried to hear from the speakers built into my laptop, but still nothing came out. I looked at all of the speaker volume adjustments and they are all up, but still nothing comes out of the speakers. I repeated this so many times and just can't find out the problem and now when I want to watch videos or listen to music they STILL don't work! Can someone help me please?