I just had a KDE meltdown thanks to swaret,
and had to download and install KDE again. On the KDE website it says you must delete your current KDE installation, Download the required packages and install them in this order.
The other packages are not required according to the website, but worth installing.
I did not delete my existing installation and took a chance and it worked fine after installing all the packages.
To install I used the Slackware ones available on the KDE download section then used Pkgtool to install them, It worked great. I then installed the other packages with no problems.