My computer has no more sound

Hello,
This is a school issued computer. I was trying to watch somrthing when I figured my sound was down. Naturally I thought it was my headphones and changed them. But it wasn't the headphones. I took the headphones out and turned the volume all the way up and I still didn't have any sound. I have dropped the computer but I have not broken any of it. Or at least I hope. Please help me...