Kdenlive gone from system, and won't re install?

I have posted this on the Kdenlive forum but been advised to try elsewhere as this seems to be an OS related issue, so here goes...

I have been using Kdenlive happily for a while on Ubuntu 14.04LTS(just 'vanilla' Ubuntu with Unity desktop). But today Kdenlive seems to have disappeared from my system!

Software Update did update a number of the KDE apps I have installed (mainly Kontact), I wonder if this is related? On trying to re install Kdenlive I get the following error:

The following packages have unmet dependencies.
kdenlive : Depends: libnepomuk4 (>= 4:4.5.85) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

I'm relatively new to Linux so would be grateful if any replies would be good enough to take that into consideration; I'm quite happy to be patronised if I learn something along the way :)

Can anybody help? I was really enjoying Kdenlive and have some projects in it I really don't want to abandon.

With thanks!