Suddenly my KDE plasma crashed. With it my panel disappeared. Restarting didn’t work, my panel was still gone.
Trying to add a new panel I notice that my plasmoids/widgets on my disappeared panel was still running, though the panel itself was no where to be seen.
How can I get my panel back. I could easily create a new panel, but I do not like the Idea that the old panel with its plasmoids/widgets might still be running in the background.
Well, if your plasmoids are still there and you can create a new panel, plasma HAS NOT crashed but is still running fine.
So the question is, why did your panel disappear?
Have you maybe removed it accidentally? In that case it would be ok to just create a new one.
Maybe the screen resolution has been changed somehow and your panel is outside the visible area?
Maybe your panel is set to autohide? Then try to move the mouse to the place where the panel should be and it should reappear.
Could you maybe post a screenshot?
If your plasma settings aren’t too customized, the easiest thing might be to just remove them:
kquitapp plasma-desktop
rm ~/.kde4/share/config/plasma*
plasma-desktop
It disappeared after plasma crashed. I did not remove it my self. The screen resolution has not changed and my panel is not set to autohide.
My screenshot, does not show much. I have two monitors.
https://docs.google.com/file/d/0B-lDdSLkpJa5NWNYZExkT3FRbmc
As you can see at the bottom, I am showing all the running plasmoids/widgets that where on my missing panel.
I managed to press some buttons and now I have gotten my self into a different desktop altogether. I have been aware of this desktop before, but not sure what it is for.
I think I just have to delete my kde plasma settings, but still would be great to find out of this without going to such drastic measure.
Well, no going back now. I deleted my plasma configuration files. Thankfully I didn’t have to change much.
Because of this something had to get broken. I am using the Icon task manager and setting it up again went without hassle. However Pinning a program with “Show A Launcher When Not Running” no longer works. I click to active, but it never gets activated.
And which KDE version are you using?
If 4.11.1 it could be this bug:
https://bugs.kde.org/show_bug.cgi?id=324661
Yes, most likely.
From that bug report it seems I can hack the settings for “Show A Launcher When Not Running” by editing plasma-desktop-appletsrc. However I cannot find out how.
The Icon-only taskmanager is in this config file as:
[Containments][24][Applets][36]
geometry=174,0,581,32
immutability=1
plugin=icontasks
zvalue=0
[Containments][24][Applets][36][Configuration]
groupClick=1
highlightWindows=true
iconScale=49
launcherIcons=true
maxRows=2
mediaButtons=false
middleClick=0
previewSize=200
recentDocuments=false
rotate=false
showOnlyCurrentActivity=false
showOnlyCurrentDesktop=false
showOnlyCurrentScreen=false
showProgress=false
showSeparator=0
sortingStrategy=1
spacing=0
style=0
toolTips=1
unity=false
[Containments][24][Applets][36][Configuration][DockManager]
Enabled=false
EnabledHelpers=
[Containments][24][Applets][36][LayoutInformation]
Order=2
Here you have to add something like this: (after the DockManager configuration)
[Containments][24][Applets][36][Configuration][Launchers]
Items=file:///usr/share/applications/kde4/konsole.desktop?wmClass=Konsole,file:///usr/share/applications/kde4/kaffeine.desktop?wmClass=Kaffeine
This example would add a launcher for Konsole and one for Kaffeine.
You could add a standard tasks plasmoid, add the launchers there and copy/paste the resulting “Items=” config line…
But don’t forget to quit plasma first before editing that file! (“kquitapp plasma-desktop”) 
And also this bug got fixed today! The fix is already in openSUSE’s packages.
So update your system (“sudo zypper up” f.e.) and adding/removing a launcher should work again even with the icon tasks plasmoid…
I just tried it and it does work here now. 