Cannot boot into desktop after purging GNOME3 PPA

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http://askubuntu.com – I am dual-booting a C2D laptop with W7 x64 and Ubuntu 12.10 x64. After using the GNOME3 PPA and getting a bit wary of the increased system instability, I tried to downgrade to the standard 12.10 AMD64 components. I installed ppa-purge and issued the command sudo ppa-purge ppa:gnome3-team/gnome3, accepting the solutions offered. However, instead of running the following additional commands sudo apt-get update sudo apt-get dist-upgrade sudo apt-get install --reinstall ubuntu-desktop I stupidly rebooted the machine. Now I can't boot into the partition. I tried the following things in Recover (HowTos)