So, more or less once every two years I simply decide that my life is not complicated enough and that it's time to mess with my laptop again.
Once I formatted my "Home" partition (don't ask why... why do you want to know why?!?), once I decided that it was time to try some new graphic drivers (nice to have the OS boot to a black screen).
Then I spend the next night/day fixing, reinstalling everything.
This time I was to install a LAMP (Linux, Apache, MySQL, PHP) on my machine... but I forgot I already installed it. And I decided that I wanted MariaDB instead of MySQL, so I tried to install it, but failed, tried to understand why, failed again (Juventus match was on... I had NO time to read the messages!), so decided to purge MySQL, but forgot that... well... it's a database that KDE uses... sometimes... like... everywhere?!? (More or less)
I wrote "sudo apt-get purge mysql*" and hit Enter (yes... I did this... I really did this... I cannot believe myself!!)... some random lines appeared, I read some and, out of utter stupidity, hit Enter AGAIN! And realized what an idiot I am.
So... obviously my KDE installation has been a little messed up.
I could recuperate something workable doing "sudo apt-get install --reinstall kubuntu-desktop", but something was still missing... like the mails?!?
This was yesterday evening... today I decided to do a new installation of Kubuntu 13.10. I use a usb drive, of course, and it took me less than an hour to have everything back.
Format sda1 as ext4 and mount as /.
sda3 is mounted as /Home.
Now I just reinstalled Steam, Skype, Yakuake, Jovie... and everything is up again. The desktop was up from the first restart. Love it!
Next time... don't purge MySQL, please!