Lost the volume/sound of my Macbook
Hello Everyone,
This morning there was no problem with the sound of my Macbook. But when I got back from school I opened the laptop(it wasn't even shut down) and I couldn't increase/decrease the sound anymore. There is no sound coming from the Macbook anymore and the icon on the top right corner is mat. When I try to increase/decrease the volume the icon on the below picture appears. The thing is that when I connect speakers or my headphone to Macbook the volume problem disappears and everything works just fine.
I did the PRAM reset by pressing the"command,alt.P,R" keys at the start up, although the opening sound works fine when the desktop appears there is no sound again...
I don't know what to do anymore. Please help me ASAP, its really urgent!!
Thanks in advance.
Macbook Pro