I have Ubuntu 8.4 and my computer would not allow me to install updates so I tried for an entire upgrade instead (to ubuntu 12.04). Everything went fine until it said "Installing New Packages" then it just sort of froze then shut down. I turned my computer back on but it didnt register my hard drive. I tried to manually mount it but it wont recognize my username/password so I cant go any further. When I simply try to skip mounting it says "mountall failed pressing control+d will reboot". I've honestly tried everything and I'm lost.