I have the same problem . I am a newbie. I added the repository with

sudo add apt-get-repository ppa:canonical-dx-team/une

then i went to ubuntu software center and installed "unity interface of ubuntu netbook edition" . after installing i found a problem with User interface as it kept on flashing when mouse points to side panel . so i decided to remove it . I removed it form Ubuntu software center . there were other unity related apps installed , but i did not remove then as i had no idea what they were about . Now i ended up with a blank white screen with mouse pointer whenever i login. though i m able to login using gdm , but the screen is blank white. I tried to these commands also

sudo apt-get remove gnome-shell

sudo apt-get remove unity

sudo restart gdm

but they did not work at all i also tried

sudo dpkg-reconfigure xserver-xorg

it too did not work. Note:I donot have any sort of graphics card or video card on my pc

please help !!!