If I press CTRL + F12 comes only an acoustic "Bing" signal, that's it then. Even through the window Addon Manager GSX is no longer.
If you hear the sound when pressing the GSX Hotkey (which is CTRL+SHIFT+F12 by default! ), it means GSX is working, assuming that's the sound you normally hear when you are trying to use GSX with engines on or the parking brakes on.
Assuming that's the sound you hear, the issue might be caused by having mistakenly turned off the Info Text from the simulator option, so GSX is trying to tell you something, but you cannot see it, because you turned off the text from the sim. Turn it on, in the simulator option.
If, instead, the "bing" sound is not coming from GSX, then it's possible ANOTHER add-on has taken the CTRL+F12 key ( UT Live maybe ? ), so you think GSX is not working, because what you assumed it was its key has been taken by another add-on. In this case, either change the key used by GSX with the "Key Mapping" menu or change the key used by that other add-on.
No two add-ons can use the same key.
If, instead, your issue is that you don't have the whole GSX or Couatl menu anymore, then it's clearly an antivirus problem, or possibly a problem of missing libraries in your system.
The thread named "Addon Manager not showing up in P3Dv4 **SOLVED**" thread lists all the known solutions for any missing menus of missing libraries:
http://www.fsdreamteam.com/forum/index.php/topic,17484.msg122656.html#msg122656