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.
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.
I had the same problem. I tried the answer from Saurav, but that did not work for me.
My panel would never show when I logged in. So I followed the instructions from Xubuntu Panels.
These are the steps that I got it going:
Press Alt+F2.
Type xfce4-panel and press Return. This brings up the Xcfe panel.
Log out of Xfce and tick the Save session for future logins button.
Worked for me.
Re-installing xfce4-panel would solve this issue
Follow these steps to re-install and re-configure xfce4-panel. Open terminal and execute these commands:
sudo apt-get update
sudo apt-get -f install --reinstall xfce4-panel
Be sure that you don't remove other packages while installing. Check the installation message carefully.
Once installed execute following command to re-configure xfce:
sudo dpkg-reconfigure $(sudo dpkg -l | grep xfce | awk '{print $2}' | tr '\n' ' ')
sudo update-initramfs -u
Then reboot your system.
It worked for me by below steps:
xfce4-panel 