One of my friends, when trying to make an USB speaker work in ubuntu 11.10+gnome 3.2+no graphics card HP machine, accidentally removed the pulseaudio driver as well as the graphics driver. So after the boot, it gives a blank screen. I tried to remove and install xorg, but it did not help. Can anyone help please?
This is a generalist way of doing things because you neglected to include hardware information, so this is a catch-all answer.
You will almost certainly need to boot to recovery mode to install the drivers. To be honest, it may be easier to back up your data and do a fresh install.