I was trying to install skype on ubuntu 12.10 desktop. but it was giving some error related to libsound2:i386 file. to overcome this problem i removed file libsound2 thinking that will install it later. but it removes all the graphics from my system. after removal of the file system started to give error that system is running in low graphics mode. I tried to install libsound2 file again but couldn't. After it i have upgraded the release of my ubuntu version using command do-release-upgrade think that it will install the missing file. But still there are no graphics on the system. I am using Dell Inspiron 15 . Please help me to tell that how can i get the graphics of system back.