Was sitting here working on the computer when the power restarted for some reason. When my computer rebooted and I signed back in my top and side panel are missing. All the rest of my desktop seems to be there. I opened a terminal and entered the command:
xfce4-panel
I got the message:
xfce4-panel: there is already and instance running
yet neither of my panels are showing up. I have tried logging out and logging back in several times and still no panel. I'm running Xubuntu 12.04 64-bit.
Best Answer
I had this problem after I changed graphics drivers. My solution was:
Press Alt+F2.
Type
xfce4-panel --preferences
and press Return. This brings up the panel preferences.Under Output, make sure that it is selected to show up on the right monitor. It might be selected to show up on an external video output or some other non-existing monitor.
Repeat this for all affected panels by selecting them from the pull-down at the top of the panel preferences window.