How do I continue configuration if apt-get was interrupted?

Use the command:

sudo apt-get -f install

If that doesn't work, you can direct dpkg to finish setting up any packages that were only partially set up:

sudo dpkg --configure -a

If it doesn't work than you can reconfigure all the packages with:

sudo dpkg-reconfigure -a

In addition to the response by @Frantique, I would like to add:

sudo dpkg --configure -a

That solved my issue when the upgrade was interrupted during the process.