can't get updates to download

The "dpkg --configure -a" is asked by the system when a previous update/upgrade process have not completely performed good, and it must run with "root" privileged administrative user.
Using the "sudo" command we can do a command as "root" user, and "dpkg --configure -a" need be run from root user.
After the "dpkg --configure -a" command i add all the usual commands (see below) you can run to be sure your system became fully upgraded.

Please also subcribe this bug https://bugs.launchpad.net/ubuntu/+source/update-manager/+bug/108601/

Typing the commands as sudo the system will ask you for a password, please give your user password when requested, you don't see nothing when you type it, then press enter.

So please be sure your system is fully updated/upgraded with no pending packages or errors:

Open a Terminal from the menu Applications → Accessories → Terminal and type:
(if the system ask you a password give your user password, you will not see nothing when you type it, then press enter)

sudo dpkg -P --force-all nameofpackage

sudo dpkg --clear-avail

sudo dpkg --configure --pending
sudo dpkg --configure -a

then to update and upgrade and also check pending or missing packages, still using terminal type:

sudo apt-get -f install
sudo apt-get --fix-missing install
sudo apt-get clean
sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade
sudo apt-get clean
sudo apt-get autoremove

Hope this helps