I have read a number of posts regarding graphics driver problems with Ubuntu (specially NVIDIA) . If you fail to install appropriate "supporting" driver for your graphics, the ubuntu may hold on Purple screen after initial boot and hangs.
to recover from the situation you may roll back the installation as follows:
1. reboot system
2. hold right shift to go for boot selection of ubuntu and then choose the recovery mode
3. after you get displayed with some options go for the root shell
4. mount the files system to access by using following command
mount -o remount rw /
5. uninstall all nvidia drivers installed by using
sudo apt-get remove --purge nvidia--*
6. Reboot system
hope you will boot with generic graphics driver.
to recover from the situation you may roll back the installation as follows:
1. reboot system
2. hold right shift to go for boot selection of ubuntu and then choose the recovery mode
3. after you get displayed with some options go for the root shell
4. mount the files system to access by using following command
mount -o remount rw /
5. uninstall all nvidia drivers installed by using
sudo apt-get remove --purge nvidia--*
6. Reboot system
hope you will boot with generic graphics driver.
