Black Screen after login

[bill blakely]

I have an old pc with a old nvidia TNT graphic card.
I installed kubuntu 12.10 (quantal) and upgraded to 13.4 (raring). Everything was fine.
One night a month ago, I went to the Muon software center and down loaded a few fonts, and some other small thing, a system monitor perhaps, I can't remember. I also dragged a web link on to the desktop.
The next time I booted up, I got the splash screen and the log in screen. When I log in, it goes black, there is a flash of what looks like a 1" x 1" browser window, then music and a cursor, and a black screen.
I have logged in as 'guest' and everything works, so assume it is my (bill) desktop that is broken.
Following suggestions on this forum, I have ctrl+alt+F1 ed, logged in and entered

startX

and rebooted to no effect.
I have

sudo apt-get install --reinstall lightdm

and

sudo dpkg -reconfigure lightdm

, and

sudo apt-get install kubuntu-desktop

, rebooting after each, all to no avail.
After install kubuntu-desktop and lightdm, I am assured that everything is up to date, "Kubuntu desktop is already the newest version" and lightdm (1.6.0 -0ubuntu3.1)
One solution would be to download and install 13.10, not a bad idea, really. But any ideas for a fix?

[Buddlespit]

Unless someone else comes with a better idea, you can try the "nuclear" fix by logging into ttl1 and deleting .kde and .cache

$ rm -R ~/.kde
$ rm -R ~/.cache
$ sudo reboot

[danix803]

Unless someone else comes with a better idea, you can try the "nuclear" fix by logging into ttl1 and deleting .kde and .cache

$ rm -R ~/.kde
$ rm -R ~/.cache
$ sudo reboot

Did this work for you or for anyone with a black screen What happens when you do that Does Kubuntu re-spawn those files