soundsticks speakers no longer work with MacBook

I have the same model computer. You have probably done all of this, but here goes. I start with a computer restart. try the speakers on another computer just to eliminate the speakers being the problem. I have had the sound quit for no apparent reason. I can't remember all the details . I'm sure I checked the sound control panel. Some apps have volume control that doesn't interact with the system settings. Safari has a small speaker icon to the right of the URL. It is only visible if the site has sound. This can be muted. I tend to have way too many tabs open and I have had multiple sites taking sound at the same time. I had to do a web search to solve that one.

Good luck.