I had previously uninstalled VirtualBox. Now, I'm trying to re-install it; but, it is not installing.
Here are my actions and results:
~$ sudo apt-get install virtualbox
[sudo] password for sudarsan:
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package virtualbox is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it: virtualbox-qt
N: Ignoring file 'virtualbox.list.save.3' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
N: Ignoring file 'virtualbox.list.save.2' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
N: Ignoring file 'virtualbox.list.save.1' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
E: Package 'virtualbox' has no installation candidate