Opensuse 11.0 KDE 3.5 No desktop effects enabled.
I lost the title bars on all my windows. The only way I could think of getting them back was to reboot. Before I rebooted I checked to see if I had desktop effects enabled. *
I rebooted and they [title bars] came back. I don’t really want to have to reboot if this happens again.
Is there anything I can do to get the title bars back without having to reboot?*
It happened on my kid’s machine when he had openSUSE 11.1 with KDE 4.1. I didn’t bother much to check whether he had messed up some desktop settings or not. (He is only 5 years old).
I upgraded his KDE to 4.2.1 and after that it is very stable.
You can check that your title bars are really “disappeared” or they just hidden. Press Alt + F3. If the menu comes out - you’ve messed up something in KDE. If there is no menu, then the title bars are definitively disappeared. 
- Probably KWin is crashed. In konsole type:
kwin --replace
.
Good luck.*
Like they say, upgrade to 4.2.1. and this will probably be solved.
What ram88 says needs some addition. You cannot do this from the console (which is reached by Ctrl-Alt-F1), because that’s on a different display than your desktop.
Try installing yakuake. It’s a terminal program, that works even if kwin or plasma has crashed. Start it once, leave as it is, and you will have a terminal window available to do a “kwin --replace” or “plasma” to get your desktop back to work again.
Oh, I’m sure that you can do this in Konsole (different desktop, yakuake - what?). When the titlebars are disappearing open a konsole window and type kwin --replace &. There is nothing to do with plasma. It’s a window manager crash. Where is your addition?