Have a look at https://wiki.debian.org/Multiarch/HOWTO
In particular, run the following in sequence:
sudo apt-get update
sudo apt-get dist-upgrade
If you still have un-upgraded packages, run sudo apt-get dist-upgrade -f
as many times as needed till all packages are upgraded. If you still have un-upgraded pacakages try continuing and see if it works. Reboot. Then run:
sudo dpkg --add-architecture i386
sudo apt-get update
To check this has been done, run dpkg --print-foreign-architectures
, and look for the output i386
. Then cycle through sudo apt-get dist-upgrade -f
again.
Let us know if this works, and if you can successfully get your desired apps working.
NOTE
Make sure you have selected the "Main Server" for downloading software and updates in the "Software and Updates" settings. I've included the screenshot below so you can see what it looks like. I'm not on Ubuntu right now so I'm not sure how to get there, but it shouldn't be so hard to find.
