Q: no sound

Please visit: http://tinyurl.com/iphonesoundhelp for help

No sound on what Mac running what version of OS X?

I have two Pro Towers (2009) running El Capitan. No sound on both.

Your problem, hardware or software, is not the same as that of the original poster of this older thread, and it can be very confusing for everybody if we try to answer more than one question in each thread, which can also result in you applying the wrong advice to your particular problem.

In order for us to give your problem our proper attention to try to solve it, would you kindly start your own thread, describing the trouble you are having in the fullest detail, including completing your details to show what Mac or iDevice you are using, what operating system, and what version of the application in question. Please remember to post in the forum relevant to your hardware or version of OS X. A full list of all the support forums is here:

http://discussions.apple.com/index.jspa