I think I had the same thing happen to me. I didn't know it but my upgrade to Kubuntu 13.10 got interrupted. When I ran the apt-get command, it told me it was interrupted and the command to run. Try this command first:

sudo dpkg --configure -a

It seemed to work for me, my network icon had a red x, my shutdown and restart buttons were gone, and my sound wouldn't work. After I ran the command, it all came back after I re-booted.