If your Menu Bar icons in Mac X Yosemite suddenly start to disappear, you may have a corrupt System UI Server preferences file. Delete the file and reboot following these steps.
1. Open Mac X Terminal
2. Type:
rm ~/Library/Preferences/com.apple.systemuiserver.plist
then
killall SystemUIServer
3. Reboot your Mac.
Your menu bar icons should show up again and you rebuild the menu bar preferences file.
Comments
This was not helping. Menu bar icons shortly show, and then all disappear. Any ideas?