Hello, I am new to ubuntu, so I was trying out various things that can be done with ubuntu. I installed Gnome desktop environment with Appgrid. I used it for a while and wanted to try KDE. I installed Kubuntu with the Appgrid. The installation was not succesful. I started experiencing problems. To be very frank I did not completely read the error messages I got. I got a lot of pop ups to report the errors to the developers. I was redirected to web pages containing confirmed bugs.

I did not know what to do, so as a naive user I restarted my system.After the restart, I get black screen every time. I do not get any login screen, I see kubuntu logo then a black screen with mouse pointer. I have tried to wait but nothing happens and I am stuck at the black screen. Although other options such as changing brightness seems to be working on that black screen. I also used to see a default pink background on my grub menu, but after getting this black screen I see black grub background.

I tried fiddling with a few options. When I boot into advance options of ubuntu from the grub menu, The generic upstart 30.0 option boots me into ubuntu with unity background. In generic upstart I tried uninstalling kubuntu with different set of commands completely ( aptitude etc) but nothing seems to work. When i try to boot into the default ubuntu option again the same black screen happens. Please help me fix this. Thank you for all the help.