The following commands are very usefull for updating ubuntu packages, installing new packages, removing packages etc when Gnome package manager gets buggy.

Just open the terminal and try the following.

1. For updating ubuntu: sudo apt-get update (no need for typing sudo if you are super user)

2. For installing a new package: sudo apt-get install package_name (here it allows wildcards like *) this searches the ubuntu repository for the package name and if present installs the package.

3. For removing the package: sudo apt-get remove package_name. It removes the package from the directory that is dedicated for storing packages in ubuntu.