If the sound on your MacBook is not working properly, there are a few things that you can try yourself to fix up your MacBook before taking it in and getting professional assistance with the issue.
#1 Reboot Your Computer
The most basic things that you can do is reboot your computer. Often times, just shutting down and restarting your computer is all you need to fix the sound issues that you are experiencing. Restarting your computer is one of the most basic ways to fix issues with your computer.
#2 Update Your Computer
The sound on your computer may not be working correctly because you have failed to download the necessary updates for your computer. To manual update your computer, click on the apple icon and find the options that says "Software Update". When you find this listing, click on it and see if there are any updates that you need to install on your computer.
The updates will most likely have to be downloaded from the internet, thus you will need an internet connection for this option. Once the updates are installed, your computer is most likely going to need to be restarted. After you do this, check and see if the sound is working on your computer now.
#3 Remove Headphones
If when you look at your volume controls and the volume control area looks grey or red, the hardware that allows the sound to work and feed into your headphones may be starting to fail. When this happens, sound may cut out to your headphones. The way to combat this issue is by taking the headphones out and replugging them. This could provide you a work around.
However, the hardware that allows sound to play into your headphones is still failing. If you want the headphone function to work consistently, you are going to need to take your computer in to get it serviced and have those components inside of it replaced.
#4 Go Into The Sound Settings
Finally, open up the system preferences on your MacBook. Within the system preferences, click on the option that says sound. Check on the speaker output and see if the internal speakers are turned on. If they are not turned on, click on the internal speaker box to turn them on. Then, look at the speaker output volume and make sure that it is turned on. Make sure that the mute box is not selected.
Try the multiple troubleshooting options listed above to get the sound working again on your computer. If these troubleshooting tricks do not work, take your computer into a mac support specialist, like one at Computer Help, Inc, to get assistance.