Obviously you have 12, so you can look in your kernel menu and see if the kernel is running - and also choose "Evaluate" from the menu (not just keys)
It is possible for you to have gone into kernel settings and hacked so that your kernel won't start or won't connect to the notebook on your desktop (i don't suggest changing the settings unless you know what your doing)
I doubt either occurred - this doesn't sound like a real problem report "yet"
