dependency problems

[Thomas Blasejewicz]

Good evening
I just made a new, clean install of kubuntu 14.04, set up 2 more
languages and made some changes under KB layouts and input methods (for
Japanese)
Otherwise I did not yet "touch anything".

Nevertheless, when I try to install new software through that "Muon"
thing, those softwares are NOT installed.
Attempts at directly installing things via terminal results in error
messages saying,
that a number of "dependencies" are not available so that nothing can be
done ...

Until yesterday, before I made some fatal error somewhere, that disabled
the OS almost completely, these things WERE working (sort of).

Where should I look / do something to get this thing back on track?

Thank you.
Thomas