I have no audio devices?

Hello, Today I was skyping my friend then when i turned the laptop off and on again the sound button had a red x and said i have no audio devices. When i click on the sound button it says it has found the problem and fixed it yet nothing is fixed. I've also tried installing the realtek audio things and updating them all but nothing works. Also it says that my high defintion audio is unplugged so what do i do?