H15; Hey ...
I will try and help you.
To understand what is going on, do in terminal:
out put shows "flashplugin-installer" as well as "adobe-flashplugin" that only tells us what packages need to be installed.
apt-cache search flashplugin-nonfree
That tells us both what we need to have installed as well as what we do not need to have installed.
apt-cache depends adobe-flashplugin
So, let us see what you do have installed:
once these are known we can remove and/or (re-)install that package the package manager is unhappy with.
dpkg -l flashplugin-installer
dpkg -l adobe-flashplugin
We are working with 'buntu's package manager within 'buntu's software repositories; between what is installed, what is available. what you want installed, what it takes in get that package installed when there now exist conflicts and/or broken packages.
All can be fixed ...But I make no promises about the continued usage of adobe-flash. I have given up on flash usage in respect to FaceBooK , YouTube and other sites requiring the latest versions of flash in order to display video !